Green Building Forum - Housing - New Build

Completing A New Build - Make It Official?

Greenfish — Thu, 08 Jan 2015 10:16:16 +0000

I seems my new build is just about complete!! Many, many thanks for all the good advice I have gained from this forum along the way. But its not over yet. The question is what do I need to do to make it official? Are there any reasons not to rush into doing so? When is a build done?

I know that BC needs to do a final visit, all the things they are interested in are now in place. But It is not my home yet, I have been "camping out" here for months while working on it yet unlikely to move in fully for several months while building wardrobes etc. But before installing "furnishings" I would like contents insurance, can I get house insurance without a completion certificate or is it BC first? As a previously used site our address is in the Royal Mail system, so we exist and get deliveries (but no junk mail!!). I admit I am not in a rush to be pestered for Council Tax before actually living here and receiving council services. Will BC trigger that?

Experiences and advice please.

SAP Assessment for a new build

Triassic — Wed, 10 Dec 2014 12:56:12 +0000

The architect has finished the building regs drawings and he tells me I need a SAP assessment, so he got a quote for the assessment and all it says is "carry out SAP assessment".

So what should I get for my money, is there a specification for a SAP assessment. Will I need to get another 'as built' assessment on completion.

Very Thin Warm Roof Challenge

thomasjamesrhodes — Fri, 04 Nov 2011 10:09:24 +0000

Hello everyone, this is my first post, though I have read hundreds of threads and learned a great deal from the forum in the past.

I am planning an extension to my listed cottage, and think I have just about overcome the planning & listed building consent hurdles, but now face the killer - building regs!

In order to get listed building consent we agreed to demolish the existing cold felt roofed extension which eats into the side of the 200 year old granite cottage. A new extension is proposed, a few metres away, with a low, glazed link room connecting them. The challenge is this linking roof must sit fully below the eaves of the existing single story slate roof (around 2.4m high). Targeting a very modest 2m ceiling height leaves not much space for a roof, but its possible.

However the good old "warm deck" roof issue has really thrown it. My plan had been 3 glu-lam beams spanning between old and new, with joists between them, filled with kingspan. This is a no-go, it seems the structure must sit fully within the warm zone, i.e. insulation all sitting completely on top. This is great where there is space, but there isnt here.

I've followed all the usual routes, begging the building controller, googling magical thin foam insulations, etc.

I can get away with this part of the roof having a U-value of around 0.3. I have some pictures I'll try and attach.

My best idea at the moment is to still use glulam, but have the structural elements breaking throught the deck, and locally clad in super duper aerogel blankets. The other idea I have (being a mechanical engineer) is making a very slim custom steel fabricated roof structure with kingspan on top. It would be a challenge even with steel.

Basically I want to bounce the idea around and hear your thoughts. I'm also pondering how they lay standing seam zinc on top of a foam roof - surely if they put a ply skin down then that is subject to the condensation that they are trying to avoid?

Look forward to hearing your thoughts
Thomas
Aberdeenshire

Cold Bridging

KateC — Thu, 08 Jan 2015 11:54:42 +0000

We are new to all this and trying to design a house extension using natural and breathable materials whilst keeping a sensible approach to affordability. We are in the north of scotland where deliveries can be expensive. Someone mentioned to me using foamglass blocks around the perimeter of the inside wall for cold bridging, someone else that this is an expensive option. The current plan is for leca base with concrete/ underfloor heating and plinth to hempcrete walls. anyone else have any ideas regarding alternatives to foamglass ?

Builder dispute - protecting the walls

malakoffee — Wed, 24 Dec 2014 08:37:38 +0000

The building of an extension onto my bungalow is in progress.

The new walls are now up near roof level, but I am planning to disengage with this builder - I don't want them extending the original roof out over the extension having seen blunders with the walls.

The walls are brick - 100mm cavity full-fill rockwool : 100mm Celcon block . . .

The builders have wandered off for their Xmas holiday with strips of DPM covering the top of cavity wall
Cavity closers are inserted in the verticals. They did not know at that point that I was calling a halt with them.

There may be a long delay of some weeks before I can get roofers in to do their stuff and protect those new walls.

It has occurred to me that I might need to protect vertical blockwork walls from the rain. Possibly by using DPM.
( The builders left some batten here for some unknown purpose, but they haven't used it. Perhaps this was to batten DPM onto the blockwork as weather protection ?? )

Toilet drain position in floor

Triassic — Tue, 16 Dec 2014 08:36:32 +0000

I'm installing the drains below a concrete slab and have just realised I don't know how far it should be away from the wall. Any guidance would be a great help as I don't have an existing one to measure.

Window selection & air permeability

ward32 — Sun, 14 Dec 2014 16:19:49 +0000

I have been looking for good performance windows and while my preferred supplier has provided all the test data I cannot find any air permeability reference information for comparison. The test window has a Uw of 0.7 and an air permeability of 3m^3/h m^2 (or 0.75m^3/h m) @100Pa.

I calculate in my design I have 20m^2 of glazing to a volume of 235m^3 so the windows alone could account for 0.225ach. But this is at 100Pa, perhaps this might be half at a test pressure of 50PA!

Can anyone point to some reference data for air permeability of windows so I can make an assessment?

New-build heating options- feedback welcome

halfmile4 — Thu, 28 Aug 2014 21:39:14 +0100

Hi all. I'm Peter, and my wife Marysia and I hoping to start a new-build in Gloucestershire over the next few months. We are in our sixties and looking to make our final (unforced) move, so design needs to be wrinkly-friendly, comfortable and cheap to run. The site is elevated, south-facing and shade-free, so ideal for maximising solar energy one way or the other. The outline planning consent at this stage seems to allow for a number of build styles, and there is already a relatively radical self-build going up on the next plot.

So far, so good, but in a way we have too many options, and the possibilities seem endless, both in house design and in 'green' options. Our particular concerns are over heating the house, and as I'm sure you all aware, for every possible solution there seems to be several opinions and even more disagreements, with few hard facts, so reaching firm conclusions will be a leap of faith.

We are planning a 2-storey build on an 11 x 8 metre footprint, with the long side pointing south on an unobstructed site in Gloucestershire. I've (hopefullly) attached a Sketch-up mock-up, not perfectly crafted, but a fair likeness. Can't see how to insert into text.

External features include the 50Âº front roof with PV or PV/solar thermal mix. Lots of south-facing glass, and little on the other sides. I'm slogging through a SAP spreadsheet at the moment to get an idea of rating. Likely to do timber-frame or SIPs with a 0.15 wall rating.

Would like a thermal mass inside- perhaps a 250mm concrete floor with wet UFH set in the slab about a third down from top. The roof and brise-soleil are angled to allow winter sun to reach back of rooms, but only a metre or so in summer. Main aim is to make things as Passiv'ish as we can afford and minimise secondary heating. Hopefully solar energy will heat a thermal water store with off-peak electric top-up as and when, and be directed under a good chunk of the ground floor when needed. There is a void above the central third of the ground floor and an open landing/gallery to help circulation of air, plus MVHR. Maybe an opening roof light for summer cooling.

I was a 'tech' teacher and have a working knowledge of control systems and have done lots of re-furbs, re-wiring and plumbing, so should be able to fit lots of the heating kit myself.

I'd be happy to expand on any of the above, and look forward to any replies- for better or worse! Thanks, Peter F

Flue Design

Triassic — Fri, 05 Dec 2014 10:33:00 +0000

We are having a wood burning stove as part of our proposed new build. The architect has just sent me the detailed drawings for comment. He has specified the stack to be constructed using clay flue liners with Will then be lined with "suppliers flexible metal flue liner".

Does this sound right? Why clay liner lined with stainless steel?

He goes on to say that the air supply should be via a presumably open vent to the outside!# I assume I can pipe an air supply to the wbs so as to do away with the hole in the wall.

What is current best practice, assuming that doing away with a wsb is not an option, according to my wife!

Internal Drainage

Cerisy — Mon, 08 Dec 2014 14:09:05 +0000

Starting to sort out the drainage inside our new build and I'm stumbling over the wall hung toilets. We'll use Geberit Duofix frames, but as the family bathroom and the en-suite are next to each other, the toilets are close to being back to back. The drainpipe sits between the metal web joists and one of the toilets will sit over the top, so an easy connection - it's getting the other into the pipe at around the same place.

The back to back bit sounds sensible, except I can't picture how the wastes can enter the main drain run at the same point. I'm clearly missing something - has anyone done a back to back installation?

Thanks Jonathan

Ridge/hip tile angles

woodgnome — Sun, 07 Dec 2014 12:33:51 +0000

Are the ridge and hip tiles usually the same angle or different?
Slate roof 35deg pitch. Dry fix.
Got a feeling they need to be different so the ridge/hip junction will be neater.
Merchant sent all universal ridges.
Any advice?
Thanks

Roof Build Up

Triassic — Fri, 05 Dec 2014 12:07:53 +0000

The architect has suggested the following roof build up for our proposed new build......

Slates
Batters
Vapour open roofing membrane draped by 8mm over rafters
Rafters
30mm air gap
Foam insulation between rafters
Foam insulation below rafters
Plaster board.

Target U-value of 0.11W/m2k

The question is, does this leave the Timber on the cold side of the insulation and would it be better to have the Timber on the warm side by putting the insulation aboutve the Timber?

Also would you go for OSB sarking over the whole roof?

Eaves Overhang Question

Triassic — Wed, 26 Nov 2014 13:07:47 +0000

I'm building a small timber frame annexe measuring 7800mm by 4800mm (external dimensions of walls). I'm looking at the roof construction and wondering how much the eaves should overhang?

Any suggestions?

Are windows a standard size

Triassic — Thu, 27 Nov 2014 22:18:47 +0000

Do Windows for new builds come in standard sizes or do I leave a hole and get a window made to measure.

Air-tight Membrane

Cerisy — Mon, 31 Mar 2014 20:49:48 +0100

After a big push - well, for two OAP's - the internal walls and four layers of insulation are nearly there. So we are approaching the air-tight membrane stage. Tapes to buy - probably from the German supplier previously mentioned - but I am still pondering the best way of sealing around the joist ends ...

has anyone had experience of sealing around metal web open floor joists? I appreciate the default position is just take my time and work around each metal element, but any useful suggestion would be welcome!!

Thanks guys - regards, Jonathan

lighting !

dickyv — Wed, 26 Nov 2014 11:45:22 +0000

Wasnt sure where to post this but as light is energy and energy is heat !!
LED downlights. Looking at the dimmable variety and have seen huge variation on pricing. Anyone know if this variation is actually valid? is product a better than product B.. see screwfix have complete units with 7 year guarantee so presumably if led fails within 7 years i get a new one. Any input most welcome

THANKS!!

Shuttering reuse

Ed Davies — Sat, 22 Nov 2014 14:19:32 +0000

Is it nutty to even think about the possibility of reusing timber used for shuttering in the actual house? Perhaps wrap it in polythene to keep the worst of the concrete off it?

Blocked Out!

Bruno — Sun, 09 Nov 2014 21:51:09 +0000

I am planning a single skin masonry wall (with EWI) for a new build and the prime contenders for the blocks are:

Hanson Fenlite
Tarmac Hemelite
Lignacite Carbon Buster
Aircrete (Celcon, Durox, etc)
Plasmor Fibolite

The first three are all very similar in terms of performance (the Lignacite are more expensive but they claim to be 'carbon negative') but they all suffer from the same problem: that because they are relatively dense, blocks of width 215mm (or even 190mm) come in at well over 20Kg per block.
The aircrete have their supporters but, as has been widely discussed on this site and others, they are susceptible to movement, don't take fixings well and are generally not as robust as a standard medium density block.
Which leads me on to the Fibolite, which seems to remarkably have all the properties of Fenlite and Hemelite, but with lower density (and therefore is less than 20Kg per block) ... and for a very reasonable price. (Where's the catch?!)
The other strategy to reduce block weight would be to go with the Fenlite or Hemelite and use 100mm blocks laid 'flat and sideways' in order to construct a 215mm wall. All thoughts welcomed on this idea please.

Finally, a quick review of why I'd like a single skin wall in the first place: it should mean a simpler, quicker construction which is far easier on which to minimise thermal bridging (and arguably airtightness) and which is future-proofed to the extent that it is far harder (impossible in most instances) to ever replace/improve the insulation on a cavity wall construction. I have encountered scepticism on the single skin construction from architect, structural engineer and builder, though none of them can provide any convincing reasons. Nevertheless, I am considering throwing in the towel and reverting to a cavity ... just for an easy life.

All comments welcomed please.

Warm roof insulation options

ward32 — Sun, 09 Nov 2014 11:05:58 +0000

I'm weighing up the options on the type of insulation to use in a warm roof construction. The roof will be made from 350mm I-joists and my original plan of using Earthwool (@0.032w/mK), full-fill, works out very expensive. I have been thinking about alternatives and am not keen on rigid boards as it will be hard to get a good air-tight fit around the periphery. How about sealing the cavities between the joists, all around, and then getting them blow-filled with EPS beads as per walls?

I can't see anything in the BBA cert about it but I shall ask the local firm that quoted for my 300mm wall fill.

Any thought welcome?

Suspended Passive floor

ward32 — Mon, 03 Nov 2014 15:08:03 +0000

I have planning permission to build and have been investigating different approaches. I have decided upon brick and block construction for various reasons and the Structural Engineer has specified a suspended ground floor due to heave potential. I have modelled my building in PHPP and the basic input data generates compliance so I am drawingÂ up the details.
Â Â
I have not found any suitable detailing for a suspended beam & block floor to achieve the sorts of U values that I would like. After lots of investigation I have drawn my own details for the floor and floor-wall junction based on the insulated floor system produced by Cube6. Their floor systems are â€œclaimedâ€ to achieve U <0.1 but I do not like their cold bridge detailing. The detailing in the attached drawing is my first attempt and I would appreciate peer review. The cavity is 250mm (was to be 300mm but PHPP is useful) and foundations have to be 1800mm (clay & trees!).

Some of questions:
1. Would I need to form a cavity tray across the XPS as I am in a low risk area for driving rain?
2. Does the concrete infill have to meet the XPS?
3. Does the concrete infill need a run-off slope and weep holes so deep down?

passive house rooflights

neilgorswift — Sat, 02 Feb 2013 10:08:28 +0000

Ive researched thoroughly Fakro v velux for triple glazed passive house rooflights and there are good threads on the forum.

Has anyone experience of ROTO they look ok and have been used on the continent for ages?

Loft Access

Cerisy — Thu, 13 Nov 2014 09:10:40 +0000

I've been looking at the various options for airtight loft hatches - I need two - with the main loft having a pull down ladder fixed to the small area of floor above (rather than the fixed to the hatch!).

Then the old mind wanders and ponders on how easy would it be to simply make them myself? Framing up the opening - simple ... hinged lid - not exactly difficult, just take my time to make it look good .... airtight seal - well, they are readily available and will require a groove cut and then a lock (or locks) fitted to ensure the hatch closes firmly onto the seals. I would also look at creating sides to protect the insulation around the access and work out a safe way of insulating above the hatch, but that would be needed even if I bought them.

Anyone else gone through the process? Any drawings available??

Many thanks, JT

Basement walls using Stepoc dry stack concrete blocks

Triassic — Wed, 05 Nov 2014 19:03:36 +0000

I'm looking at the various basement construction methods and someone on here mentioned the use of Stepoc blocks, these are dry stack concrete blocks which are then filled with concrete. I've looked at the web site http://www.andertonconcrete.co.uk/websitecontent/stepoc.aspx but it's a little light on details.

So if you have used them, what is the typical wall cross section, where did you put your insulation (type) and how did you waterproof the basement wall?

Surecav units

Triassic — Wed, 05 Nov 2014 22:44:42 +0000

The gable ends of our build will be constructed using local stone to meet a planning condition. The architect has suggested the use of Surecav units rather than blockwork. Has anyone got any experience of using Surecav, pros and cons etc?

http://www.surecav.com/en-GB/video_2.aspx

Do all Ali Windows have Joints Siliconed to make Airtight?

Gotanewlife — Mon, 10 Nov 2014 15:18:35 +0000

Just had 2 triangular windows installed. One is just a single fixed pane. I can see outside through every single joint. I understand that making odd angles is tricky but even the 90 degree ones have straight through cracks. They will be back tomorrow am to add silicone of about the right colour. The ali profiles are thermally broken.

Looking at the way these profiles are cut it seems to me that there is no way to avoid every joint being a route for air, without either siliconing each joint or having some sort of gasket (which would be ugly and I have never seen before). And the joints we are talking about are simply butt joints of 2mm + or - aluminium sheet hardly the most effective long lasting solution, especially where the gap itself is as much a 1mm wide.

I hate silicone unless sandwiched between 2 solid flat surfaces because longevity is measured in months, or a year or 3, whereas window frames should last a bit longer than that! I really need my expectations managed because I trusted these guys and they did deliver against a ferociously tight deadline. So, is it the case that all ali window frames are constructed with silicone at the joints. If so, Uw values would surely be highly dependant upon the skill of the fabricators and subject to deterioration over a short timescale (relative to the life expectancy of the frame). They also fitted the DG units 'dry' up against the ali profile and suggested that it would be better if I added a bead of silicone outside myslef!!!! Would there normally/always be silicone at this joint, or a gasket (such as a narrow version of the one fitted inside)? Very grateful for some timely advice before I blow some fuses, burn some bridges and lose some sleep. Ta.

Best Energy Company for the construction phase of a New Build

richardelliot — Thu, 09 Oct 2014 14:52:00 +0100

Hi,

Site clearance has finally started for my new build and the builders are going to get going on the foundations in mid-November. I have booked in the connection of a temporary power supply with UK Power Networks and now need to organise an energy company to come and install the meter and supply me with electricity.

I have two questions I'm hoping the forum can help me with:
1. Can anyone recommend a good energy company to be with during the build phase?
2. I have no idea how much elecricity building a house will use. If I go down the price comparison route do you think I should use low, medium or high consumption as a ball park option?

I'm currently with Ebico for my home supply and happy with both their customer service and pricing so they'd probably be my default option.

Thanks,
Richard

LED lights

neilgorswift — Wed, 23 Jan 2013 13:44:04 +0000

Photon star LEd's are state of the art reliable GB technology. Does anyone know of other quality but good value alternatives for "on a budget LED" scheme?

initial airtightness test

djh — Tue, 04 Nov 2014 12:33:26 +0000

We just did our initial airtightness test of the empty house (no internal walls etc).

0.26 ACH average (corrected). We're thinking of doing the final building regs test with a window open :bigsmile:

Windpost cold bridging

ward32 — Wed, 05 Nov 2014 12:30:42 +0000

My S.E has told me I need to have windposts in several position for wall length (wind load) and large openings (structural support around bi-fold doors). I am building a 300mm fully filled cavity with Teplo type 2 ties and to put steel links between the leaves is not good thermally, although they might just prevent the house falling down. I have looked at some standard types from the likes of Ancon and they all tie on to both leaves. A U shaped post in the middle of the cavity (fixed to footings) and tied to the leaves seems to offer the best thermal performance as it would be in the middle of the insulation, but not ideal.

All the windpost systems I have seen are either built in to the inner leaf, bolted to it or sit in the cavity. Is it possible to fit a windpost to the inside face of the outer (brick) leaf, bolted to the foundations and supported by the concrete infill (>1m). I could then perhaps add addition Teplo ties to strengthen the bond between the leaves.

Any ides?

Critque my new build wall section

Triassic — Mon, 03 Nov 2014 21:20:35 +0000

I've just got this wall cross section from the architect and he's asked me for comment, so I thought I share it with you to see what you thought of his proposal?

Soil testing - lead content in soils

richardelliot — Thu, 30 Oct 2014 09:38:23 +0000

Site clearance has started on my new build project and my contractor advised that no one would take away the soil we need to have removed without it being tested.

The test results came back yesterday and they are showing led levels across the site of between 340 mg/kg to 520 mg/kg. There is also a localised spot where an old garage used to be that is higher.

I'm struggling to find any information online which states what is a safe level vs. what needs to be remediated. I've found a few links which suggests these are failry typical levels for London gardens, but I was hoping to find an 'authorative' source like Environment Agency guidance.

The soil testing company are advising it all needs to be removed to a depth of 60cm and replaced with inert soil. I don't know if this is required or they are being overly cautious.

Has anyone experienced anything similar? Could you point me in the direction of what are deememd safe background levels of lead in soils?

Thanks,
Richard

Air Tight?

dickyv — Thu, 30 Oct 2014 11:44:19 +0000

Going up in a few weeks a timber frame "air tight" house.
having gone down this route (air tight MVHR) how do i ensure any holes made in external walls are sealed correctly? Bit of a novice and really hope spray foam is NOT the answer :)

Insulation strategy for Earthen Walls

stulutions — Sun, 26 Oct 2014 02:36:38 +0000

Greetings,

I am currently designing a natural house for the cold climate in Saskatchewan, Canada, using Compressed Earth Blocks.

The greatest complication in this is how to insulate?

Strategies I am considering:

Straw bales on the exterior but in combination with an already 12" thick wall, that will lead to some seriously thick walls, as well as involving a 2nd labour intensive process to an already labour intensive build.

Double Wall construction, with a natural insulation infill such as cellulose, wool, or rice hulls. Wool and hulls would involve some transportation and its associated embodied energy, not to mention the fact that they are not "local"

Hempcrete on the exterior wall---havent fully learned of its potential applications as I am awaiting a reply from inquiry to a Hemp tech company. Seems like it is a redundant doubling of thermal mass though?

Cork - expensive and not local

Flax - Ive not yet contacted the local company doing work on using it, but to my knowledge they haven't yet got the insulation product side of it down yet - though I believe in the UK you have companies doing so?

Foregoing a natural insulation for a high performance material such as xps, rockwool, etc. and pretending that the environmental costs of these materials are minimised through the rest of the build design and the fact that the house will last hundreds if not thousands of years (give or take :wink: )

I eagerly await your thoughts and advice. This is my first post on the forum but about 5 years ago, I went through many thousands of your informative posts in a 1 month period of being glued to a computer!(thanks!)

Warm Regards,

S

How hot can the â€œextractionâ€ water be for a standard heat pump?

ringi — Wed, 22 Oct 2014 17:25:30 +0100

I have been thinking and dreamingâ€¦.

I know that a heap pump gives a better COP if the â€œoutputâ€ temperature is as close to possible to the temperature of the water it is taking heat from. A better COP leads to a lot better government payment. I also understand that a big issue with water based solar inter seasonal store is the insulation and that having lot of luke warm water is not of much value.

So why not combine the two?

Use the inter seasonal store for UFH while it is still warm enough.
Then use the inter seasonal store as the â€œinputâ€ to the heat pump while it is still warmer then the ground
Then use the ground loop.

However the few heat pumps I have looked at in passing having a max input temperature of 15c that is too low.

New Build Ideas?

Victorianeco — Sat, 18 Oct 2014 20:41:48 +0100

Current situation is I've sold my existing house while I'm in the process of renovating my new one.

However, I have just came across this plot of land locally with planning permission for a 4 bed house:
http://www.rightmove.co.uk/property-for-sale/property-44762948.html

I have no idea on the feasibility of me obtaining a mortgage for such a project, but I'd love to build my own house at some point and if I sold my renovation project once complete I'm sure I could do something with my equity.

So questions:

1. What type of design would you go for on a plot that size? I'd like a modern, highly efficient ecohome but would probably need to blend in with surrounding houses (in the pictures)
2. What is the average cost to build say a 3 or 4 bed house to suit said plot?
3. Anything you think I should research first?

Fire protection spray for timber cladding

LondonEcoHouse — Sun, 12 Oct 2014 19:55:27 +0100

Hi All,

We have built a small 2 bed house in SW London and are struggling with the final hurdle being new build warranty (Premier Guarantee) & building control sign off on our timber cladding.

We have clad the house in rough-sawn, untreated larch and originally had a product which could be spray applied to the larch that was going to meet our fire protection requirements.

What Premier Guarantee also require is a 15 year guarantee on the product, but the product we were going to use was only guaranteed for 10 years.

Building control now want us to take off the cladding and fit supalux underneath it to meet the fire protection standards but we are still left with needing to apply something to the timber that has a 15 year guarantee and 45 mins fire protection.

With hindsight we would have done things so very differently but a huge lesson there to be had.

Has anyone had the same challenge or is aware of a product that might give us what we need with the 15 year guarantee please?

Without it we may need to remove the lovely timber cladding we have and are being pushed down the route of having to clad it in some kind of cement fibre board which seems a horrible option to us.

Anny help is much appreciated.

Thank you
Peter

volume house builders attitude to insulation

db8000 — Wed, 08 Oct 2014 14:29:13 +0100

Is well exemplified in this bbc programme:
Http://www.bbc.co.uk/iplayer/episode/b04knnhf/inside-out-west-06102014
From 10mins 35secs

In short, Charles Church (Persimmon) converts a listed building Muller House and according to the BBC's findings, doesn't bother with the insulation.

Someone though has told the EPC assessor it was insulated. Buyers upset.

Scraping ice off the inside of the windows!

I know EPC has it's flaws but even on the incorrect assumption, it scored lower than my largely unaltered Edwardian detached house!

Lead Valley on Sarking detail

woodgnome — Wed, 01 Oct 2014 19:19:34 +0100

Has anyone got any details of a lead valley with 22mm sarking and counterbatten/batten?
Looked online but nothing seems to be the right one.
Does the sarking provide enough support for the lead,
or do i need a valley board on the sarking?
Thanks.

Noggins - Needed or Not

Triassic — Thu, 25 Sep 2014 10:37:19 +0100

I've just got the drawings back from the structural guy doing the calculations and he's specified 9.5mm OSB sheathing and noggins at 600mm centres.

I'm sure I read somewhere (if only I could remember where!) that noggins are not required when using an OSB sheathing layer?

Can someone point me in the right direction?

Eaves question

woodgnome — Tue, 23 Sep 2014 21:45:17 +0100

Can anyone recommend a way to finish off this eaves detail to maintain airtightness.
200 full fill cavity with Isover CWS.
Panelvent or Gutex 18mm sarking on top of trusses with membrane on sarking/ counter batten/ batten/ slates.
Truss depth filled with rafter roll meeting up with wall insulation. OSB/ VCL/ 50mm Eps or similar under truss, battened service void and plasterboard. 18mm ply soffit on top of truss to leave exposed truss ends, no box ends at gables.

Thanks

Rustic Polished Concrete

Leao16 — Sun, 21 Sep 2014 21:51:02 +0100

Hi, I want to create a 'rustic' polished concrete floor in my bathroom, similar to the attached image.

It's very similar to 'acid stained polished concrete' but less refined. I've lost touch with the person who did the floor in the attached image but I remember him telling me that it's an old Roman technique involving lime.

There is also another much darker rustic polished floor technique that I would like to explore for my bathroom. It's common in France and Spain for countertops and sinks and it has a very dark (almost black) rustic texture. I think it involves diamond polishing a mixture of cement and earth and adding a black ash product to create the dark effect, but I can't find any examples online :sad:

Do you have any idea what the technical names are for these techniques are so I can find more examples and instructions on the net?

Cheers!

Leao

Adding internal insulation to SIP

divorcingjack — Tue, 04 Feb 2014 17:22:17 +0000

Hi all,

We are planning to use SIPs for our self build and I'm currently trying to develop strategies to improve the U value and decrease the thermal bridging. The manufacturer has offered a couple of suggestions - using a thicker panel and/or using a reflective breather membrane and a foil VCL.

What are people's opinions on adding another 75-100mm of celotex/kingspan to the internal face of the SIP. I have read a lot of discussion about adding extra insulation to the outer face and the condensation risk that it poses, but not much about adding it internally. If we were to do that, how would we go about it? I don't really want to batten out twice, and where would we put the VCL to avoid it being punctured by services and plasterboard fixings?

My theory is that adding the extra insulation would bring down the U value to approx 0.1 and combat some of the thermal bridging, although the manufacturer is already using insulated splines so hopefully the bridging at panel joints shouldn't be too bad. Unfortunately, due to the plot size and planning restrictions, our house is a non-optimal shape, so I'm keen to make the most of reducing the u values where I can.

Thanks for any input, this forum is so flipping helpful!

divorcingjack

Late 1950 modernist architecture made greener?

Fjord — Mon, 15 Sep 2014 10:02:02 +0100

Hello to everyone at this amazing forum!
I just signed up to hopefully take part in the exciting discussions regarding green builds.
I have studied architecture and I'm very interested in the era of the 1950-60's modernist buildings and would like to build my own home one day featuring some of the typical design features of this period.
While studying architecture very little focus were on the actual construction so I know almost nothing about the subject! :confused: So I hope I can get a little help here!
I have started sketching a house with a flat roof and slender fascia (~300mm total thickness)with a large 100cm overhang. I have tried to find information on how to actually construct something like the attached photos without too much thermal bridging happening. (it seems like i can only attach one photo per post?)
With my limited knowledge I see the challenge with this construction method that the joists need to puncture the thermal envelope to form the large overhang. I have tried to find a way to improve this and have worked on a way to make it seem like the joists continue from the side to the outside, but they're actually cut to stop the thermal bridge. I hope my drawings make some sense as English isn't my first language and writing technical build lingo isn't my biggest skill.

I know the glazing will be bad in regards to heat transmission but I have found some triple glazed units (36 mm with krypton filling: 0.5 W/m2K) and they seem to be improved all the time so maybe a fairly good thermal envelope could be created sometime in the near future.
Trying to find a solution to this thermal envelope problem got me thinking if it's even worth the effort to eliminate the thermal bridge in the joists when the heat transmission is so much higher in the glazing it self :/

I would love your comments on a minimal construction like this. I haven't decided if I would like to be able to see the construction joists as in one of the referenced photos or if I prefer the minimal continuous surface, but I guess the underlying construction will be the same/similar?

I know the part of the build is just one of many many design challenges, but I need to start somewhere.
Thank you for reading! :)

Eaves Details: new build with EWI

Bruno — Sun, 14 Sep 2014 21:57:37 +0100

Hi all,

I'm new here and, although this topic has been covered in previous threads, I can't find suggested eaves details online that fit my planned spec, and I wonder if anyone can point me in the right direction, because I don't want to reinvent the wheel if a consensus solution has already evolved.

My setup is as follows:

Detached house, with rooms in the roof
Aircrete single-skin 215mm block walls, with 200mm EPS EWI
Hollowcore concrete floors
Airtightness target: <1
Roof to be insulated over-rafters (to meet EWI), probably with an inter-rafter contribution too
Proficient airborne soundproofing - since we're on a (minor) flightpath
Roof U-value target: 0.11
No requirement for a significant eaves overhang
Roof finish will be clay tile
Hipped roof, with a central table-top flatroof (with a good fall designed in and a top-quality membrane)
[Other misc details, in case it helps: square footprint, bay windows to front (with hips over), two dormers, and several south-facing rooflights]

To recap, I'd like to find any commendable eaves details that complement the above spec. (They must exist)!

If I have any specific related questions, they would be:

1) Should we cut the rafters short at the wall plate or carry them through, and accept the thermal bridge? (And does anyone have any quantitative suggestions as to what difference this 'actually' makes, thermally)?
2) If we stop the rafters at the wall plate, do any roof boards exist that allow direct fitting of fascias and gutters? (I'm hesitant to pursue a solution involving cantilevered mini-rafters and such).
3) Traditional rafters or engineered timber?

All comments gratefully received!

sip architect

flexon — Wed, 10 Sep 2014 12:45:46 +0100

Hi all
I am new to forum and new to self build I am embarking on a very small bungalow 10mtrs x 9metrs to be constructed on greenbelt land my problem is I know very little about my chosen material and neither doese the retired draftsman I have engaged to do my drawing although we are not too far down the drawing route im wondering if i should cut my losses and try to find someone who is knowlagable in sip constuction or trust that the company i decided to use to make my pannels will interprate his drawings sufficiently.
I think what im trying to get to is there anyone one here that could recommend s architect in the wirral erea who may be better suited to my needs ie sip construction and the stricked requirements of building on greenbelt lsnd.
Sorry for being so long winded but my situation is a lot more complicated than I have time or space to go into here.

How good is water proof concrete?

Triassic — Thu, 04 Sep 2014 23:17:11 +0100

We are considering using ICF to construct the walls of our basement. It has been suggested we use water proof concrete, but is it any good? Would I need an external membrane as well and would this stick to EPS?

How best to tank new basement

Mike George — Sat, 03 Apr 2010 10:45:14 +0100

Any ideas on the greenest solution to tanking a new build basement? Many thanks in advance, Mike

External insulation for basement walls

stephendv — Fri, 09 Jan 2009 19:51:43 +0000

What type of insulation is suitable for using for below ground basement walls? The walls themselves will be poured concrete and I'd prefer insulation externally since it means I won't need to build interior basement walls.

Constructing a basement in a limestone area

Triassic — Wed, 17 Apr 2013 06:42:18 +0100

Has anyone got any experience of building a basement in a limestone area?

I'm planning to construct a full footprint basement on a sloping site, open on the downhill side and full cover at the rear (north side). Anyone got any advice on most cost effective construction method / spec, how difficult is it to excavate limestone (maybe 1.5m worth), likelyhood of ground water.

I'm thinkling of constructing a 1 1/2 storey bungalow over the basement. Is it best to have block and beam floor over the beasement to provide fire protection?

I was also thinking of a solor heat sink under the basement - any suggestions?

floor levelling and height adjustment

djh — Wed, 10 Sep 2014 21:16:21 +0100

I have a feeling I may be starting a series of threads that all look the same ... but this one is about the best way to build my ground floor.

The structural ground floor is a concrete slab, sitting on a big bunch of EPS. The slab isn't perfectly level or smooth - perhaps up to 10 mm max variation - though it is reasonably flat. I also need to build it up by 65-75 mm to finished floor level. (The height difference is the threshold height of a lift-and-slide door and the desire to achieve level thresholds). So my problem and question is what is the best way to build up the floor level?

'Best' may mean cheapest, or perhaps there's some other criterion like buildability to be taken into account.

I think there are two fundamental ways to build up the level - screeding or battens. But there are lots of options - sand and cement screed or self-levelling? And is the self-levelling a thin layer plus battens on top or is it full height. Finished floor will be a mixture of some or all of these surfaces: carpet, lino, tiles, engineered timber, cork, bamboo. They all have different thicknesses and strengths/requirements for support. One room will be a shower wet room. Others are kitchen, utility, dining, living and a bedroom.

I'm not sure how much I should care about introducing thermal resistance between the slab and the floor surface, nor even certain whether more resistance is good or bad. I'm not planning on UFH.

I think the way to go is separate floors in each room. This allows for different build ups for the different surfaces, and will be easier to build I suspect.

But what do you think? What options should I be considering?