Green Building Forum - Resale value of wooden residential homes

Resale value of wooden residential homes

Magpie — Mon, 18 Jan 2021 13:52:10 +0000

I am hoping to get planning permission to build a low allergy home at the end of my garden.
I am currently researching potential construction materials as I have to avoid a lot of chemicals, such as formaldehydes, which are also contained in the glues many construction materials such as glulam, plywood etc
Brick is a safe option, but I suspect labour costs are high. I am considering a modern â€œlogâ€ cabin type house, but am wondering about the resale value, as I canâ€™t afford to invest in a home that loses value upon sale. Does anyone have any views or information on resale values and construction types?

Resale value of wooden residential homes

Cliff Pope — Mon, 18 Jan 2021 14:10:03 +0000

Residential home?

Resale value of wooden residential homes

Doubting_Thomas — Mon, 18 Jan 2021 14:26:47 +0000

We built in Cross Laminated Timber (note that many of the more recent product options do not use formaldehydes any more, polyurethane adhesives are far more common due to flexibility).

There are related methods such as dowel-laminated (brettstapel) that don't use adhesives but this is still fairly 'fringe' and therefore difficult to find the contractors.

Our biggest hurdle was actually the mortgage advisor who'd never heard of CLT and was convinced it wouldn't be on the council of mortgage lender's list of approved constructions. We passed that hurdle and are now paying for it with higher insurance premiums, since again it's not a 'common' construction.

That said, I don't really have any regrets, it was fast and relatively painless process. We now have a lovely exposed timber finish. We had to paint it with a translucent fire-retardant paint but this was water-based and WELL-standard accredited etc.

It's worth looking into MVHR as this will significantly reduce your exposure to airborne pollutants (there are HEPA filters available).

Given the cost of CLT, if that is a concern you may be better off looking at more standard timber frame options with timber panels for racking resistance. FosterTom on a thread here has previously shown a method using OSB and polyurethane glue which would be significantly cheaper I suspect. If you don't like OSB (due to adhesives/VOCs) we used Elka Strong Board (ESB) instead: https://www.ecologicalbuildingsystems.com/product/elka-strong-board-p5-particle-board

Resale value of wooden residential homes

Doubting_Thomas — Mon, 18 Jan 2021 14:33:17 +0000

Posted By: Doubting_ThomasFosterTom on a thread here has previously shown a method using OSB and polyurethane glue

Found it!

Photos about halfway down this page, note this was 2017 and I think some opinions will have changed on things like Icynene (not as good as it seemed at the time). Still, the general approach is still sound. There was mention of using flat metal strap over the joints instead/as well I seem to recall.

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14931

Resale value of wooden residential homes

Magpie — Mon, 18 Jan 2021 14:50:22 +0000

I need to avoid all glued products because of the preservatives in glues as well!
Iâ€™m not too keen on MVHR because of the risk of mould in the ducting, and outdoor pollution from woodburning stoves everyday (despite people having gas central heating). I know you can get filters but it gets a bit high maintenance. I prefer to open the windows if the outside air is clean.
The brettstapel looks interesting, although I take your point about unusual construction methods and issues with loans and insurance.
Does all exposed internal timber have to be painted with fire retardant paint?

Resale value of wooden residential homes

Doubting_Thomas — Mon, 18 Jan 2021 15:12:46 +0000

Posted By: MagpieI need to avoid all glued products because of the preservatives in glues as well!

Not all adhesives are created equally so I would spend some time investigating the polyurethane options since this is widely touted as 'non-toxic'. MVHR will also remove a lot of the off-gassing potential since the whole volume of air in the house is replaced every few hours.

There is also nail-laminated timber which some engineers are looking at reviving: https://www.thinkwood.com/mass-timber/nlt previous comments about brettstapel apply here.

Posted By: MagpieIâ€™m not too keen on MVHR because of the risk of mould in the ducting, and outdoor pollution from woodburning stoves everyday (despite people having gas central heating). I know you can get filters but it gets a bit high maintenance. I prefer to open the windows if the outside air is clean

There is almost no risk of mould in the ducting, since (done right) the ducts are all warm as inside the thermal envelope so any condensation occurs inside the unit where it is drained away. Added to which, the physics of MVHR and moisture-content in warm vs cold air means you almost have the opposite problem - dry air.

The outdoor pollution aspect is precisely why I prefer MVHR. We live next door to neighbours who literally burnt tractor loads of waste, not just timber but old electrical goods etc. during lockdown. If we were stuck with opening windows in warm weather we'd have had to bring un-filtered air straight into the house. As it was, the filters did the hard work and removed the worst of the particulates. They were basically black from smoke at the last change.

Speaking of changing filters, it is really straightforward - swap out a paper rectangle every quarter. Less hassle than emptying the hoover!

Posted By: MagpieDoes all exposed internal timber have to be painted with fire retardant paint?

It depends on the amount you have on show and the size of the room. We were determined to 'see our investment' in the CLT and went for a semi-translucent coat to improve the rating everywhere. You can plasterboard over the top instead but we weren't keen on this. If you want to leave it completely un-treated, the Building Regs Approved Document B 1 states:

"4.4 Parts of walls in rooms may be of lower performance than stated in Table 4.1, but no worse than
class D-s3, d2. In any one room, the total area of lower performance wall lining should be less than
an area equivalent to half of the roomâ€™s floor area, up to a maximum of 20m2 of wall lining."

In reality that usually means covering some of it up with something.

Resale value of wooden residential homes

djh — Mon, 18 Jan 2021 15:49:36 +0000

Posted By: MagpieI need to avoid all glued products because of the preservatives in glues as well!

It would probably help if you could explain a bit more about your need to avoid certain products. Is your concern due to a medical problem? How do you find out which products you need to avoid and which are OK?

Iâ€™m not too keen on MVHR because of the risk of mould in the ducting, and outdoor pollution from woodburning stoves everyday (despite people having gas central heating). I know you can get filters but it gets a bit high maintenance. I prefer to open the windows if the outside air is clean.

As Doubting Thomas says, there's no risk of mould on a well-installed MVHR system and there's less risk of outdoor pollution than through other ventilation methods such as opening windows. You will almost certainly need some sort of mechanical ventilation system if you build an airtight dwelling.

Resale value of wooden residential homes

Magpie — Mon, 18 Jan 2021 16:01:29 +0000

Thank you for all your comments, which have been very enlightening.

Yes I have medical conditions which make me extremely sensitive to minute amounts of chemicals

My bete noir (apart from formaldehyde, mould and smoke) are isothiazolinones, which are the go-to EU preservative for water based products - paints, sealants, glues, nearly all DIY products unless solvent based. Of course solvents tend to be high voc.

Lime products are good - I have considered limecrete, but again the question of loans, insurance, and resale values

Everything also has to be low maintenance because supermarket laundry products on contractorsâ€™ clothes usually contain isothiazolinones, so I need to be able to maintain everything myself as much as possible

Resale value of wooden residential homes

Victorianeco — Mon, 18 Jan 2021 18:36:05 +0000

How do you test for such allergies to such materials?

Resale value of wooden residential homes

Peter_in_Hungary — Mon, 18 Jan 2021 19:17:42 +0000

I would go for a single skin block construction with EWI. I don't know if EPS is acceptable from the point of view of VOCs but there is a lot less VOCs with EPS than other solid sheet insulation boards, also the EWI EPS being outside and covered with a render may not be an issue. But of course there are other EWI materials such as mineral wool.
The advantage with this type of construction would be mainstream construction methods whereby it's bread and butter stuff for local builders and lenders won't throw a wobbly because it is not a typical construction. Also IMO a block wall with EWI is much harder for a builder to muck up than a timber frame construction

Resale value of wooden residential homes

CWatters — Mon, 18 Jan 2021 20:00:51 +0000

Posted By: MagpieI need to avoid all glued products because of the preservatives in glues as well!
Iâ€™m not too keen on MVHR because of the risk of mould in the ducting, and outdoor pollution from woodburning stoves everyday (despite people having gas central heating). I know you can get filters but it gets a bit high maintenance. I prefer to open the windows if the outside air is clean.

I think that strategy is more likely to cause issues. Best thing we ever did was put an MHRV system in our new build. The constant fresh air keeps humidity down and reduces condensation and mould. If you've ever been camping it feels like waking up in a tent. Much happier with air quality than in any previous house. Our MVHR doesn't even have very fancy filters, just a coarse filter to keep out flies and wasps etc.

The other good move was reducing the number of carpets. We have stone floor in living room and kitchen. Engineered wood in dining room and hall. Tiled bathrooms etc.

Surprised you are considering a modern log cabin as sure a lot of the structure will use pressure treated timber.

Resale value of wooden residential homes

djh — Mon, 18 Jan 2021 20:08:12 +0000

Posted By: VictorianecoHow do you test for such allergies to such materials?

Contact allergy tests.

Resale value of wooden residential homes

GreenPaddy — Mon, 18 Jan 2021 20:37:19 +0000

Magpie, that sounds like a total nightmare, if even the contractors clothing is enough to set off a reaction.

It's seems quite a specific problem, that might mean you taking the lead with what materials you can use, and then perhaps come back to the forum and ask how we might help you piece them together.

Would straw bale construction be a possibility, at least as a way to get the structure up, without man-made chemicals...but I guess you'll maybe have concerns about what it might have been sprayed with in the field? It "could" be a bit more DIYable, as it's a skill you could train to do, reasonably forgiving I'd have though, and one that is not readily available, so might as well DIY. Lime render inside and out?

DJH might have useful pointers, if you thought that could be a possibility?

Resale value of wooden residential homes

djh — Mon, 18 Jan 2021 22:04:05 +0000

Posted By: GreenPaddyWould straw bale construction be a possibility, at least as a way to get the structure up, without man-made chemicals...but I guess you'll maybe have concerns about what it might have been sprayed with in the field? It "could" be a bit more DIYable, as it's a skill you could train to do, reasonably forgiving I'd have though, and one that is not readily available, so might as well DIY. Lime render inside and out?

DJH might have useful pointers, if you thought that could be a possibility?

I thought about the possibility but I wouldn't recommend it. There's a lot of unique issues that would be made a lot more complicated by severe allergies such as it sounds like Magpie has. I think PiH's idea of blockwork with EPS externally is likely to be a lot more practical solution, and it seems to me that employing builders is likely to lead to less contact with VOCs and other 'substances' than DIY of any kind.

Resale value of wooden residential homes

revor — Tue, 19 Jan 2021 09:35:40 +0000

I remember seeing a Grand designs episode a while ago where a family had issues with a couple of children (may have been twins) suffering from severe allergies and built a house think it was in London outskirts a challenge in itself. They sourced materials that were allergy free for the whole build down to the furnishings and everything that went into the house. They had an MVHR with special filters I recall. Try finding a reference to it and see what might be there to learn. Think it was a costly build but it was big, small may be the way to go.

Resale value of wooden residential homes

jfb — Tue, 19 Jan 2021 10:05:20 +0000

Or just a cavity wall construction rather than single skin and external wall insulation.

I know the latter has its advantages but I would suggest that most builders are more comfortable with cavity wall than single skin.

Resale value of wooden residential homes

Doubting_Thomas — Tue, 19 Jan 2021 10:50:27 +0000

Magpie,

For some further reading you might want to look into getting a copy of this book:

https://newsociety.com/books/p/prescriptions-for-a-healthy-house-3rd-edition

I bought it a few years before building my own house and whilst it is heavily US-focussed the principles involved apply wherever you are in the world. There are sections on the various parts of a house and a fairly good assessment of the material options available.

I'd recommend tracking down a secondhand copy as it's not cheap for what it is, but worth a read.

As a caveat, it's a bit like reading a Medical Diagnosis book - you may end up reading it and convincing yourself there are even more potential pitfalls everywhere, but treated with a healthy dose of pragmatism it could help inform some of your decisions.

Resale value of wooden residential homes

Magpie — Tue, 19 Jan 2021 11:35:04 +0000

More food for thought.

If buying a â€œlog cabinâ€ it would have to be untreated - there are a few around. Larch is a good option for me

Does anyone know of eco blocks that are structural - not cinder or slag waste

Polystyrene insulation is not really an option - there seem to be a few natural eco options, although I would like to avoid those treated with flame retardant or chemicals

One interesting option is an untreated softwood timber frame, with hempcrete walls/insulation - either as blocks or cast on site

Resale value of wooden residential homes

djh — Tue, 19 Jan 2021 12:35:36 +0000

Posted By: MagpieDoes anyone know of eco blocks that are structural

What do you mean by an 'eco block'?

One interesting option is an untreated softwood timber frame, with hempcrete walls/insulation - either as blocks or cast on site

Hempcrete is a good choice, IMHO. I'm not sure I'd be happy with a completely untreated timber frame, especially the sole plate. You have to consider that it may/will get soaked at some point during construction and perhaps afterwards (e.g. we had a minor flood from our washing machine a few days ago) just by water draining through the wall. I'm happy that all our timber below floor level is treated, although everything major above ground is untreated. But battens behind untreated WRC cladding are treated for example. It may be possible to design to use untreated everywhere, but I would want to be very sure.

I just found an interesting site. It seems a bit disorganized but has a lot of information http://what-when-how.com/Tutorial/topic-135753o5iin/The-Hempcrete-Topic-Designing-and-Building-with-Hemp-lime-bookmark.html

Warmcel may be another useful blown-in insulation, though not in quite the same way as hempcrete.

Resale value of wooden residential homes

Peter_in_Hungary — Tue, 19 Jan 2021 12:49:48 +0000

Posted By: jfbOr just a cavity wall construction rather than single skin and external wall insulation.

I know the latter has its advantages but I would suggest that most builders are more comfortable with cavity wall than single skin.

The problem with cavity wall is that there is a lot of opportunity for builders to make a thermal mess of the cavity, single skin block and EWI is easier to get right (and easier to see the workmanship in progress).

Posted By: MagpiePolystyrene insulation is not really an option - there seem to be a few natural eco options, although I would like to avoid those treated with flame retardant or chemicals

Rockwool can be used for external insulation and shouldn't have the chemicals of polystyrene and is non-combustible without added chemicals

Resale value of wooden residential homes

Magpie — Tue, 19 Jan 2021 16:02:13 +0000

Thank you for all the input, which has led to some more research.

There is inevitably some difficulty in reconciling the need for low toxicity (brick, glass, stone, timber, wool, hemp, lime are best), cost, performance, and being sufficiently mainstream to be acceptable for loans, insurance and resale value.

Internal block with external insulation and a lime render seems a possibility. I agree with jfb - cavity walls are best avoided - I presume the cavity would have to be filled with insulation to comply with building regulations energy requirements, which would not be desirable for several reasons

Are there any eco loadbearing alternatives to the usual concrete blocks?

Resale value of wooden residential homes

djh — Tue, 19 Jan 2021 17:27:23 +0000

Posted By: MagpieAre there any eco loadbearing alternatives to the usual concrete blocks?

There are lots of systems. It depends what you mean by 'eco' and how exactly you want to use them.

Resale value of wooden residential homes

Mike1 — Tue, 19 Jan 2021 18:44:49 +0000

Posted By: MagpieAre there any eco loadbearing alternatives to the usual concrete blocks?

Naturally dried clay bricks. Or, built in-situ, cob or rammed earth.

Also see https://www.bre.co.uk/filelibrary/pdf/projects/low_impact_materials/IP16_11.pdf

Resale value of wooden residential homes

Peter_in_Hungary — Tue, 19 Jan 2021 20:08:21 +0000

Posted By: Mike1
Posted By: MagpieAre there any eco loadbearing alternatives to the usual concrete blocks?

Naturally dried clay bricks. Or, built in-situ, cob or rammed earth.

Also see https://www.bre.co.uk/filelibrary/pdf/projects/low_impact_materials/IP16_11.pdf

None of these are mainstream building techniques which will cause problems downstream with resale, loans etc.

Posted By: MagpieAre there any eco loadbearing alternatives to the usual concrete blocks?

The main building block over here is Porotherm, a fired clay honeycombed block that is load bearing. They are available in the UK and there are other brands available. I have just had an extension put up, single story flat(ish) tiled roof and the construction is 250mm Porotherm blocks and 200mm external insulation.
I am not sure if Porotherm are more eco than concrete but certainly lighter and easier to work with.

Resale value of wooden residential homes

Doubting_Thomas — Thu, 21 Jan 2021 17:49:10 +0000

On the subject of Porotherm (or Ziegelblocks/Thermoplan), there are some Passivhaus constructions that use them too. If you can reduce the ongoing energy use of your building for years in the future, this is arguably more important to the 'eco' question than whether the concrete or clay brick has more embodied carbon.

The online IBO Bauteilkatalog has a couple of standard build-ups (AWm-05 Perforated brick), which google translate can help to decipher:

https://translate.google.com/translate?hl=en&sl=de&u=https://www.baubook.at/phbtk/&prev=search&pto=aue

Plus a solid brick option (AWm-04b) with hemp fibre insulation, that I imagine might translate across as a means of insulating with more benign materials.

Resale value of wooden residential homes

djh — Thu, 21 Jan 2021 22:17:03 +0000

Posted By: Doubting_ThomasThe online IBO Bauteilkatalog has a couple of standard build-ups (AWm-05 Perforated brick), which google translate can help to decipher:

https://translate.google.com/translate?hl=en&sl=de&u=https://www.baubook.at/phbtk/&prev=search&pto=aue

Plus a solid brick option (AWm-04b) with hemp fibre insulation, that I imagine might translate across as a means of insulating with more benign materials.

Thanks for that link. I hadn't seen it before, although google translate does make it a bit weird to operate. I also notice there is now a version of the book specifically for renovations "Details for Passive Houses: Renovation: A Catalogue of Ecologically Rated Constructions for Renovation (Ecological Refurbishment)" that may be interesting for some people. There are also some interesting door details, including balcony doors.

It's interesting to note that AWm-05a (using EPS) is rated as slightly ecologically better than AWm-05b (using mineral wool) but looking in my 2008 paper copy of the book I don't see how they arrive at that - it seems to show EPS being worse on a number of measures.

The main difference in the ecological rating of either version of AWm-04 and AWm-05 is the difference between using fired clay bricks (Porotherm) and unfired clay bricks. EPS and hemp seem to score almost the same ecologically.

Resale value of wooden residential homes

WillInAberdeen — Thu, 21 Jan 2021 23:25:28 +0000

I think the carbon intensity of electricity has dramatically decreased since 2008, so the balance has swung away from minimising energy usage for heating (the original passive house approach) and has swung towards minimising embodied carbon emissions in building materials.

How far it has swung, is up for debate. Ideally minimise both, or even sequester carbon in the building fabric by using a lot of wood.

Resale value of wooden residential homes

djh — Thu, 21 Jan 2021 23:32:55 +0000

Posted By: WillInAberdeenI think the carbon intensity of electricity has dramatically decreased since 2008, so the balance has swung away from minimising energy usage for heating (the original passive house approach) and has swung towards minimising embodied carbon in building materials.

I agree with that. That's the opposite way the AWm-05 assessment seems to have changed though. EPS is now good and mineral wool is bad but previously it was the other way around. It's a puzzle and it's too late to solve it tonight.