Housing - Renovation: Edwardian House Renovation

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- CommentAuthorMatBlack
- CommentTimeOct 22nd 2019 edited
Hello all,

Stumbling upon this forum has been a great help in getting ideas for our home renovation. We have bought a 1905 semi thats in need of a lot of tlc - damp, rotting floor joists, leaky roof, tanking plaster, cement mortar to name just a few issues.

First jobs will be to make it watertight - new roof (with loft conversion), fix guttering and divert water with french drains. Then repoint with lime mortar (solid walls), and new sub floors. Then knock all the tanking plaster off and install wood fibre internal insulation and lime plaster. Then on with rewiring/central heating etc.

With the 2 reception room floors however, I cannot decide whether to replace the floor joists and insulate, or go for the foamed glass with limecrete and ufh. Its a 700mm void, so the glass is expensive. But in the long run the heating efficiency may pay off - its just that Ive read some accounts of nightmare installations with the glass insulation!

So anyway, looking forward to being a forum member, hopefully I may be able to give some help one day once this renovation is done.
- CommentAuthorNick Parsons
- CommentTimeOct 23rd 2019
Welcome to the Forum!

You will find a lot of help here. Your 'recipe' is very much what I usually recommend, in terms of wood-fibre and lime pointing.

I can see from the front elevation why you want to do IWI (internal insulation of external walls), but does this necessarily apply to the gable and the rear? How about external insulation (EWI)?

Are you doing this yourself, with contractors, or a mix of both?

If you have not used wood-fibre before I can share experience with you. Here's one for a starter - try to get all/the majority of elecs on internal walls!

Insulation of suspended timber floors can be a pain, and the insulated results appear not always to obey the laws of physics! You may sleep more easily at night with a solid (ish) floor. It does not *have* to be foamglass and lime, though I accept that there is a proven and certified model which does not involve sheets of plastic. I assume (from the fact that you have not mentioned it) that you are trying to avoid concrete? If you will allow me to mention it, I just had a whimsical wonder about a 'floating floor' lay-up of (concrete??) slab/membrane/wood-fibre/OSB/finished floor. I haven't had time to think that through, and obvious issues relate to compressive strength, moisture at base and perimeters etc etc, but (if not for you) it may be a possible idea for future refurbs where people are trying to get good thermal performance avoiding plastic and (possibly) concrete.

Good luck, and have fun. I am just about to walk into my W-F-insulated front room which 'feels' and smells so much nicer than the rest of the house (insulated 30+ years ago with XPS and EPS).

Nick P
- CommentAuthorPile-o-Stone
- CommentTimeOct 23rd 2019 edited
Posted By: Nick ParsonsIf you have not used wood-fibre before I can share experience with you. Here's one for a starter - try to get all/the majority of elecs on internal walls!

I've done one room so far with wood fibre IWI and agree with the above. I've also moved the radiator from under the window and put it onto an internal wall (this also allowed me to reduce the length of the pipework to the radiator and positions the radiator centrally in the room). I'd also agree with Nick about maybe fitting EWI on the rear and perhaps at the side of the property if you can. It's more effective and you don't have to worry about dew points and all that. Less disruptive to do the work too, especially if you're considering fitting more efficient windows.

With the floor, we fitted limecrete (NHL 5) with leca rather than foamed glass and fitted underfloor heating. We're very happy with it. At the time foamglass was a bit too expensive. If I were doing it now I'd probably use foam glass as it's great to use a recycled product and it'd have a higher u value. If you're concerned about how deep the void is, could you not part fill it with hardcore and then fill the rest with foam glass to a level that meets/exceeds building regs?

The advantage of a solid floor is that you don't have to worry about ventilation under joists or any dampness and the underfloor heating future-proofs the house if we all convert to heat pumps. It's also nice to wander about in bare feet on a warm floor.

Good Luck, and maybe consider keeping a blog to show progress? I have one and I find that it helps keep me motivated and serves as a reminder of how far I've come. Plus it might be useful to others on the same journey:

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15384&page=3#Item_30
- CommentAuthorMatBlack
- CommentTimeOct 24th 2019 edited
Thank you for the welcome and replies!

Nick, I am going to try and do a fair bit myself - wood fibre, elecs and plumbing and general stuff, and use contractors for things like the roof and potential limecrete, plastering and boiler installation. Although I would really like to learn to lime plaster.

Its good to hear the woodfibre is a worthwhile result, I'm sure plenty of questions will surface as I go! I never really considered external insulation, but will now have a good look at it for the rear.

Pile-o stone - its so reassuring to hear the solid floor with ufh is working well for you. Mmmmm...I wonder if side installed EWI could be tapered in towards the front edge?

Good idea with the half fill of hardcore, and I'll have a look at the leca too. I'll be reading your blog with interest, would love to do a youtube one but not sure I'd be up to that!

Today I've managed to squeeze a couple of hours in chasing the tanking plaster from the wall in one room, its a start...

And Petlyn, thanks, I'll keep it in mind.
- CommentAuthorGreenPaddy
- CommentTimeOct 25th 2019
MatBlack, have a look at vermiculite as your solid floor insulation. I think...

Leca lambda = 0.1 W/mK

Vermiculite lambda = 0.06W/mK

So vermiculite thermally better (ie. need less of it), and I think it was cheaper, last time I looked. Not researched the green-ness of vermiculite, though I guess energy in blowing clay bubbles might be significant?

Something less than 400mm would get you well below 0.15W/m2K floor Uvalue - it's tricky calculating floor Uvalues as perimeter/area ratios, edge insulation, allowance for subfloor, etc. The Uvalue is much better than just the straight material lambda/thickness.
- CommentAuthorPetlyn
- CommentTimeOct 25th 2019
The other alternative to both Leca and vermiculite is a recycled expanded glass bead.

As GreenPaddy has already stated, the lambda value of vermiculite is better than Leca - glass beads have a similar 0.0661 value but with the added advantages of not absorbing water (vermiculite is used to retain water in planting situations) and with a high compressive strength - they do not settle or deteriorate after installation.
- CommentAuthorMatBlack
- CommentTimeOct 26th 2019
<blockquote><cite>Posted By: GreenPaddy</cite>MatBlack, have a look at vermiculite as your solid floor insulation. I think...

Leca lambda = 0.1 W/mK

Vermiculite lambda = 0.06W/mK

So vermiculite thermally better (ie. need less of it), and I think it was cheaper, last time I looked. Not researched the green-ness of vermiculite, though I guess energy in blowing clay bubbles might be significant?

Something less than 400mm would get you well below 0.15W/m2K floor Uvalue - it's tricky calculating floor Uvalues as perimeter/area ratios, edge insulation, allowance for subfloor, etc. The Uvalue is much better than just the straight material lambda/thickness.</blockquote>

Hi GreenPaddy, thanks for the suggestion, I could see vermiculite being useful in filling the voids, but not sure of its compressive resistance as a structural feature of a solid floor? however I did see a vermiculite concrete mix which I have never seen..
- CommentAuthorMatBlack
- CommentTimeOct 26th 2019
Posted By: PetlynThe other alternative to both Leca and vermiculite is a recycled expanded glass bead.

As GreenPaddy has already stated, the lambda value of vermiculite is better than Leca - glass beads have a similar 0.0661 value but with the added advantages of not absorbing water (vermiculite is used to retain water in planting situations) and with a high compressive strength - they do not settle or deteriorate after installation.

I also can see the benefit of these beads in a void fill with joists scenario, so thanks. I think at the moment I am leaning towards a solid floor, so I think it will be a mix of hardcore, then leca or foamed glass, then lime slab with ufh. I'm not sure glass beads would be suitable for a loadbearing floor?
- CommentAuthortony
- CommentTimeOct 26th 2019
Ground bearing slab could work, I would go Compacted hardcore, 300mm eps sheets with perimeter insulation 25 pir, vb/dpm, concrete 120, 150 or 100mm screed 60mm
- CommentAuthordjh
- CommentTimeOct 26th 2019
Generally you can think of all these small-bead-like insulants as equivalent for structural purposes under something that spreads the load like a con/lime-crete slab. Even EPS beads will be loadbearing given a suitable slab over the top, I expect.

EPS blocks are used to build railway embankments, because they're cheaper than hardcore, and very stable.
- CommentAuthortony
- CommentTimeOct 26th 2019
EPS sheets are virtually incompressible, beads are not, nor is vermiculite and that has been mentioned, it will squish back to mica thicknesses.
- CommentAuthorMatBlack
- CommentTimeOct 26th 2019
Posted By: djhGenerally you can think of all these small-bead-like insulants as equivalent for structural purposes under something that spreads the load like a con/lime-crete slab. Even EPS beads will be loadbearing given a suitable slab over the top, I expect.

EPS blocks are used to build railway embankments, because they're cheaper than hardcore, and very stable.

Oh I see, thanks for that.ðŸ‘
- CommentAuthorMatBlack
- CommentTimeOct 26th 2019
Posted By: tonyGround bearing slab could work, I would go Compacted hardcore, 300mm eps sheets with perimeter insulation 25 pir, vb/dpm, concrete 120, 150 or 100mm screed 60mm

Thanks Tony, that would certainly be a cheaper (and easier to install) option, but do you think concrete hinders the 'breathability' of the building, in the lower walls etc. Having no direct experience with these type of houses I just assumed from what I've read that vapour permeable floors are more suited?.
- CommentAuthorMatBlack
- CommentTimeOct 26th 2019
Could I ask another question if I may.
I knocked the last of the tanking plaster off today, and as such have got only partial lime plaster now. (+1m up in parts)

I have knocked all the lime off (ðŸ˜) where I'm installing the woodfibre. But elsewhere, is it worth matching what lime plaster I have left on the walls, or knock it all off and start afresh.
- CommentAuthortony
- CommentTimeOct 27th 2019 edited
Redo it with lime matching it up tap walls with your knuckle, pull of any hollow sounding bits over masonry.

Re breathing floor limecrete would be an option

If the substructure is damp or wet and the house warmer than the ground and surroundings then it will dry out

Floors with voids are usually ventilated so they tend to stay dry.

Walls with tanking and cement pointing canâ€™t breathe so tend to be damp, they even collect moisture from the house.

Are the walls breathable on the outside?

There is a niggle in my mind about your U-values, will you be looking for sign off on the works?
- CommentAuthorsquowse
- CommentTimeOct 27th 2019
<blockquote><cite>Posted By: djh</cite>Generally you can think of all these small-bead-like insulants as equivalent for structural purposes under something that spreads the load like a con/lime-crete slab. Even EPS beads will be loadbearing given a suitable slab over the top, I expect.

EPS blocks are used to build railway embankments, because they're cheaper than hardcore, and very stable.</blockquote>

That's not the reason they're used for embankments. Reason is that the settlement is much less and quicker. The soil in an embankment is heavy and compresses slowly. Also the soil underneath compresses due to the weight of the new embankment.
So they're used especially where you are widening or replacing part of an existing embankment so as to avoid differential settlement.
- CommentAuthorMatBlack
- CommentTimeOct 27th 2019
Posted By: tonyRedo it with lime matching it up tap walls with your knuckle, pull of any hollow sounding bits over masonry.

Re breathing floor limecrete would be an option

If the substructure is damp or wet and the house warmer than the ground and surroundings then it will dry out

Floors with voids are usually ventilated so they tend to stay dry.

Walls with tanking and cement pointing canâ€™t breathe so tend to be damp, they even collect moisture from the house.

Are the walls breathable on the outside?

There is a niggle in my mind about your U-values, will you be looking for sign off on the works?

Cheers Tony,

The lime is very soft on the brick at the moment, pull a loose bit off and it just keeps on coming!

Got all the tanking off now, just the cement mortar to get out and repoint with lime. Yes all the walls are breathable externally.

With the U values, I'm a bit concerened too, definately will be over the 25% for plastering & building control. And it looks like woodfibre cant quite reach the values either. I'll call bc up tomorrow and have a chat about it, see if a theres any wiggle room.
- CommentAuthorvord
- CommentTimeOct 28th 2019 edited
Mine is partly Edwardian and I've removed tanking from soaking wet walls, made them breathable inside and outside, lowered external ground levels to below internal. Th walls took many months to dry. I used 60mm woodfibre in a lime levelling plaster - fibreboard - lime plaster set up. Those walls are still nice and dry now.

The insulation doesn't meet the target U values in regs, but building regs accepted that imperveous insulation would act much like the tanking and keep the walls wet which wouldn't be good for the building.
- CommentAuthortony
- CommentTimeOct 28th 2019
Lime plaster is always soft and easy to remove , leave as much on as you can

Half way up the stairs is a good place to practice tapping to find hollow bits
- CommentAuthorMatBlack
- CommentTimeOct 28th 2019
Vord - Awesome to hear, looking forward to getting it on the walls! Hopefully bc will see that same reasoning here.

Tony - cheers, I'll be much easier on the existing lime now (especially getting the woodchip off)
- CommentAuthorNick Parsons
- CommentTimeOct 28th 2019
Hi, you said:

''I have knocked all the lime off (ðŸ˜) where I'm installing the woodfibre.''

I'm not quite sure why. I always install wood-fibre on top of a full (min 6-10mm) parge - air-tightness - coat of lime, not just on the 6mm-toothed-trowel adhesive coat (which to my mind does not always give a reliable 'fit' to wobbly walls). If the exg plaster is lime I treat that as the parge coat and simply make good the bits that have fallen off or were never there (such as behind skirtings, between floor etc).
- CommentAuthorMatBlack
- CommentTimeOct 28th 2019
Posted By: Nick ParsonsHi, you said:

''I have knocked all the lime off (ðŸ˜) where I'm installing the woodfibre.''

I'm not quite sure why. I always install wood-fibre on top of a full (min 6-10mm) parge - air-tightness - coat of lime, not just on the 6mm-toothed-trowel adhesive coat (which to my mind does not always give a reliable 'fit' to wobbly walls). If the exg plaster is lime I treat that as the parge coat and simply make good the bits that have fallen off or were never there (such as behind skirtings, between floor etc).

Hi Nick, it was an ill- thought out desicion at the time of weilding my 6kg makita around all day chopping the tanking off...ðŸ˜€. Especially with the lime progressively coming off, I just thought "start fresh with these walls" wasnt without doubting myself, thinking this is going to cost me! In hindsight and the comments here I should have left as much on as possible!
- CommentAuthorPetlyn
- CommentTimeOct 28th 2019
Returning to the floor insulation topic, we have used the expanded glass beads entirely successfully to provide an insulated sub-floor for electric heat mats below bathroom tiles. When combined with a small amount of sand and cement and mixed in a concrete mixer a perfectly robust insulative screed can be achieved with a plain sand/cement skim or self-levelling compound before tiling or other surface finish. We this will give a better insulative value than Leca, used in a similar fashion. Our floor screeders had also used glass beads in place of Lytag when pumping an insulated screed,
- CommentAuthorMatBlack
- CommentTimeNov 26th 2019
Been a bit slow lately, had the roof done although its not 100% finished. For some reason they left the eaves exposed, but he's coming back to put a strip or compo them in.

The chimneys are in dire need of flaunching and repointing, so I'll get some nhl 5 and 3.5 for those.

Got to drop the liners for the gas stoves, (decided against a wood burner).

May I ask, does anyone have an opinion on filling a quite deep subfloors. Option one is 3-400mm hardcore, 300mm glass foam, then 100mm lime screed. Option two is 6 - 700mm glass foam (compacted in layers) and then the screed. Option one is cheaper by a long way - but do you think the weight of the hardcore will affect the retaining walls, and possibly solem floor? the mot type 1 is 2.2 ton per cubic metre, and I need around 9m3.

Is it safer to just use all glass foam.
- CommentAuthortony
- CommentTimeNov 26th 2019
The fill will be ok in terms of being retained by the walls, with that thickness it is likely to settle a bit almost no matter how well you compact it. Do NOT use sand blinding.
- CommentAuthorMatBlack
- CommentTimeNov 26th 2019
Posted By: tonyThe fill will be ok in terms of being retained by the walls, with that thickness it is likely to settle a bit almost no matter how well you compact it. Do NOT use sand blinding.

ok thanks Tony, especially the sand blinding advice. would the settling happen over months or relatively quickly?
- CommentAuthortony
- CommentTimeNov 26th 2019
Years rather than months, if weâ€™ll compacted mm only, if not well compacted more. Need to check for clay heave and organic matter in the ground.
- CommentAuthorMatBlack
- CommentTimeNov 26th 2019
much appreciated! it might be worth me doing it all in glass then, if theres less room for error!
- CommentAuthorMatBlack
- CommentTimeJan 21st 2020
Its been a while, but Ive been busy ripping out still. I'll add some photos soon.

All the lath and plaster ceilings are down, these had been overboarded in places already, with small woodscrews, the overboards basically fell off with a bit of a nudge. I want to add insulation before re-boarding.

200mm+ of uninsulated concrete coming up this week in the back room and old kitchen. Hallway tiles up and soil dug out. To be dug to 300mm and then either 200mm eps or glassfoam, with limecrete. Or even 200m eps and concrete. All with UFH.

150-200mm hardcore in the two rooms with voids, ready for my indecisive filling of choice. Was going for glass and limecrete with ufh. But more last minute wobbles have me considering eps and concrete - can it be that bad to have concrete and a dpm, if I'm making the walls as breathable as I can? If cost was no issue at all it would be glass + lime. But pricing it all up, unfortunately theres a considerable difference!

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