First timers attempting an ICF and Oak Frame house in Devon

[MCoops]

Hello all, Matt & Hayley here. 

Last year we bought a sloping plot in Devon (the slope has caused more issues than anticipated), with a barn on (infested with bats and birds, cue further issues... and cost, obviously), this year we are hoping to finally start building! 

We have planning for a 4 bed detached house, made of Oak, with an ICF outer - it seems this hasn't been done much before, so this will be interesting. 

 

We've done a few renovations before, but never built the actual walls, so this part is all new to us!

 

Thanks

[Conor]

Hi. Welcome. Lovely looking site!

 

What do you mean by oak with ICF outer? 

[MCoops]

Hi, thanks  

 

We've got a structural green oak frame supporting the upper floor and roof, all visible internally. Then we're building the walls with ICF on the outside. We toyed with sips but weren't fans. We are sip paneling the roof though. 

[ToughButterCup]

2 hours ago, MCoops said:

...

We have planning for a 4 bed detached house, made of Oak, with an ICF outer - it seems this hasn't been done much before, so this will be interesting. 

...

 

Welcome.

What a gorgeous photo. 

By .... outer ... do you mean with ICF in between the oak timbers ( bit like a half-timbered house ) ? In which case we need photos of the plans ( or pdfs.)

We're nosey you see. ( Well I am )

 

Anyway, good luck. 

Here's a link to a  search for the term   ICF   on this site. I suggest it because the site-search takes a bit of getting used to.

A bit of quiet fire-side reading if you have time.

[MCoops]

1 hour ago, ToughButterCup said:

 

Welcome.

What a gorgeous photo. 

By .... outer ... do you mean with ICF in between the oak timbers ( bit like a half-timbered house ) ? In which case we need photos of the plans ( or pdfs.)

We're nosey you see. ( Well I am )

 

Anyway, good luck. 

Here's a link to a  search for the term   ICF   on this site. I suggest it because the site-search takes a bit of getting used to.

A bit of quiet fire-side reading if you have time.

 

Hello! We were trying some site navigation last night. We'll get used to it. Definitely not much on here about Oak builds, just porches and extensions. 

 

We were hoping to just fill in between the Oak like your traditional Tudor buildings, but with all the regs it just isn't possible. You just can't meet SAP/U Value regs. It's also a massive thermal bridge, and can track water, so no, the ICF will be encapsulating the Oak. Which is a shame, you need to pick whether you want the Oak on the outside or inside essentially, unless you do two frames, but we're not millionaires unfortunately. 

 

We have got an Oak balcony, so a little will be visible from the outside. 

 

Thanks for the link. Got some reading to do!  

23_ProposedHouseElevation_South_RevB.pdf 24_ProposedHouse_Floorplan_Ground.pdf 25_ProposedHouse_Floorplan_First.pdf

[MCoops]

1 hour ago, ToughButterCup said:

 

Welcome.

What a gorgeous photo. 

By .... outer ... do you mean with ICF in between the oak timbers ( bit like a half-timbered house ) ? In which case we need photos of the plans ( or pdfs.)

We're nosey you see. ( Well I am )

 

Anyway, good luck. 

Here's a link to a  search for the term   ICF   on this site. I suggest it because the site-search takes a bit of getting used to.

A bit of quiet fire-side reading if you have time.

Here is the Oak design - not been 100% finalised yet. 

Oak design final.pdf

[ToughButterCup]

Quote

 .... so no, the ICF will be encapsulating the Oak ....

 

😔

[twice round the block]

Nice idea..... but you are building the house twice.

Your building first with ICF.

Then your building the same house with an oak frame.

 

I've recently spoken to Oakwrights about doing oak detailing in a conventional brick and block build. That way your not paying for the build twice, but still getting the effect in chosen rooms.

 

Oak frames can make room designs hard, as the frames get in the way of placing furniture and maximising available space. You only have to look on various Oak frame manufacturers websites to see some of the issues you face.

 

If you do a full ICF build you can have oak engineered flooring,oak doors, oak kitchen etc, and your only paying for the build once.

 

[JohnMo]

Would think you are making life difficult and possibly way more expensive. You will have a structural oak frame AND a structural ICF doing nothing more than window dressing.

 

I make a decision on ICF or oak frame and go from there. Not sure I would mix. Oak is flexible and will move about initially or will in the green state, the ICF is concrete there is no flex.

[SteamyTea]

Welcome.

Is it the look/style of oak beams you like, rather than the structural integrity?

 

If it is just the looks, build in ICF, timber frame, even stuck build it, then make up some fake oak beams (oak veneer or box), then stick them in place.

 

Remember that with ICF you are forking out a large amount of cash at the start of the build, and it is not unknown for ICF companies to go bust.

Also, ICF is not Lego. It usually needs specialized input from real engineers.

Edited January 30 by SteamyTea

[Mr Punter]

What a great plot!

 

I understand the attraction of oak.  It is a traditional natural material.  Sadly for a house structure it does not work well as it is hard to achieve decent insulation and airtightness.  There are loads of other options, so keep an open mind.

 

You could always have an oak framed workshop / garage if you have the space.

[Alan Ambrose]

There’s not so much love on ‘t ‘ub for oak frame. There are a bunch of oak frame companies in business so someone is clearly buying their products. But those buyers are not on here. Similarly Baufritz houses etc.

 

I have a design with a structural oak frame ‘clad’ with larsen-truss style insulation. Makes a lot of sense to me.

 

The self-build magazines have loads of oak frame builds. Some have brick skins, some clad in other materials including render, oak featheredge etc. SEs who understand oak frame are fairly rare, but some get it. I think it’s fairly common for the frame to support the roof directly, and the walls to be self supporting.

 

The 4 big guys - Oakwrights, Carpenter, Welsh and Border have loads of experience with all sorts of configurations - so pick their brains.

 

You can probably go through planning without making a final choice of ‘cladding material’ - just the look and feel (and constraints imposed by the oak frame).

 

We live in a barn conversion currently and want to get the feel of raw oak (and other earthy materials) in the new build.

[jack]

21 hours ago, MCoops said:

Here is the Oak design - not been 100% finalised yet. 

Oak design final.pdf 192.86 kB · 16 downloads

 

Your personal details are on that doc (and maybe some of the earlier ones you posted). If you can provide versions without the details I can re-upload them for you (you can only edit your posts for half an hour after posting).

[Iceverge]

@MCoops

 

Welcome to the site. 

 

Congratulations on planning and a balanced straightforward design. For the large glazed windows facing south I would favour something like French doors and avoid bi-folds as they're very drafty. 

 

I really love OAK frame but the pauper in me doesn't like the reality of doubling up on the structure. I'm fermenting an idea that could be economical to execute though. I'll sketch it later if I get a chance. 

 

I'm not a huge fan of SIPs, so I can see why you've decided against them for the walls. Why have you decided to keep them for the roof? 

 

ICF ticks lots of boxes but it's not without it's pitfalls too. The one I'm concerned about most is the exterior render directly onto the EPS in damper climates. 

 

There's some quite new houses near me where it's failed. @ProDaveunfortunately had a similar situation over his woodfiber. 

 

The transition between rendered surface and cladding on the facade will need some consideration too to avoid a very large step. 

 

Keep posting and good luck. 

 

 

 

[Redoctober]

20 hours ago, twice round the block said:

Oak frames can make room designs hard, as the frames get in the way of placing furniture and maximising available space. You only have to look on various Oak frame manufacturers websites to see some of the issues you face.

 

 

This is exactly what we found when researching our build. We looked very closely at Border Oak but just couldn't make the remaining wall space work for us with a "frame" that was within our budget. So, like a few others here, we have incorparted "oak" in to our TF house with a stone external wall - Even to the point of introducing two 4 metre oak beams into the main rooms downstairs. Not structural, just aesthetic. 

[Simon R]

It looks as though you've found a lovely plot, good luck with your build

Along with a couple of the other comments, building an oak frame within and ICF structure will add considerable cost and complexity. Like you my wife and I had some renovation experience, doing a build was a steep learning curve. With a lot of help from the folks on build hub we ended up building with ICF. It's worked out well for us, we used JUB ICF which is a little different from most ICF solutions as they cut all the blocks in the factory. A little more expensive but it reduces risk, for example all window opening are millimetre perfect. ICF isn't lego, construction is pretty straight forward, filling the walls with concrete is not and definitely requires an experienced contractor.

We blogged our build on build hub and also added a thead on the ICF system we used.

 

[Susie]

Hi and welcome, looks a nice plot but no doubt a few challenges with the slope and wildlife. 
im over near Bude doing an ICF build and have a blog on here about it. 
I need to update the blog as the roof is now finished but no windows yet.

 

[MCoops]

On 31/01/2025 at 13:13, jack said:

 

Your personal details are on that doc (and maybe some of the earlier ones you posted). If you can provide versions without the details I can re-upload them for you (you can only edit your posts for half an hour after posting).

Hi, I don't think they are - just the oak framing companies details, which is all over the web anyway. The previous docs are all on the planning portal also, so already in the public domain. Thanks for pointing it out though. 

[MCoops]

On 30/01/2025 at 17:36, twice round the block said:

Nice idea..... but you are building the house twice.

Your building first with ICF.

Then your building the same house with an oak frame.

 

I've recently spoken to Oakwrights about doing oak detailing in a conventional brick and block build. That way your not paying for the build twice, but still getting the effect in chosen rooms.

 

Oak frames can make room designs hard, as the frames get in the way of placing furniture and maximising available space. You only have to look on various Oak frame manufacturers websites to see some of the issues you face.

 

If you do a full ICF build you can have oak engineered flooring,oak doors, oak kitchen etc, and your only paying for the build once.

 

Yes, we are essentially building the house twice. That's pretty much how is goes if you want an Oak frame that meets regs. It was a similar cost to SIPS to be honest, which is what most OAK houses seem to be skinned with, but we weren't a fan. The rebar and lintel design in the ICF isn't as much as it would normally be - it's only bearing the windows and doors, the upper floor and roof are hung on the Oak, so the Oak is the main structure.

We've designed the house and rooms around the Oak already, so space and placement of things shouldn't be an issue. We did speak to Oakwrights about it, but their costs were eye watering, and they didn't seem interested in any custom design - they wanted you to pick a house from their catalog kind of thing. That was our impression anyway. 

[MCoops]

On 01/02/2025 at 21:55, Susie said:

Hi and welcome, looks a nice plot but no doubt a few challenges with the slope and wildlife. 
im over near Bude doing an ICF build and have a blog on here about it. 
I need to update the blog as the roof is now finished but no windows yet.

 

Ha, no doubt indeed! I didn't envisage investing £3k in bats but here we are! I'll have a look at your blog. We love Bude - looking forward to being close to it. 

[MCoops]

On 31/01/2025 at 13:33, Iceverge said:

@MCoops

 

Welcome to the site. 

 

Congratulations on planning and a balanced straightforward design. For the large glazed windows facing south I would favour something like French doors and avoid bi-folds as they're very drafty. 

 

I really love OAK frame but the pauper in me doesn't like the reality of doubling up on the structure. I'm fermenting an idea that could be economical to execute though. I'll sketch it later if I get a chance. 

 

I'm not a huge fan of SIPs, so I can see why you've decided against them for the walls. Why have you decided to keep them for the roof? 

 

ICF ticks lots of boxes but it's not without it's pitfalls too. The one I'm concerned about most is the exterior render directly onto the EPS in damper climates. 

 

There's some quite new houses near me where it's failed. @ProDaveunfortunately had a similar situation over his woodfiber. 

 

The transition between rendered surface and cladding on the facade will need some consideration too to avoid a very large step. 

 

Keep posting and good luck. 

 

 

 

We've had bifolds before (albeit the cheaper end of the market ones) but we weren't that impressed, so we are looking for either a french or patio door style I think - to be decided! 

They're the easiest way to do the roof with how the Oak frame is. A cut roof is much harder to achieve, and insulate we've found, and the less exposure to the elements the Oak has the better - so timescale is on the mind too. At least a roof is a serviceable item, more so than walls, so if there are any issues we can get to it. 

 

The render issue with woodfiber is interesting. The more we research it the more this comes up - it seems whilst the concrete inner itself doesn't track water, the woodcrete does absorb it while out in the elements during construction. And it's then difficult to get it to dry because we plaster and render etc, and it can't breathe, so the plaster and render fails - real pitfall for something that has legs. We'd batten before any render, and are also battening out the render / clad levels too. 

[MCoops]

On 30/01/2025 at 19:42, Alan Ambrose said:

There’s not so much love on ‘t ‘ub for oak frame. There are a bunch of oak frame companies in business so someone is clearly buying their products. But those buyers are not on here. Similarly Baufritz houses etc.

 

I have a design with a structural oak frame ‘clad’ with larsen-truss style insulation. Makes a lot of sense to me.

 

The self-build magazines have loads of oak frame builds. Some have brick skins, some clad in other materials including render, oak featheredge etc. SEs who understand oak frame are fairly rare, but some get it. I think it’s fairly common for the frame to support the roof directly, and the walls to be self supporting.

 

The 4 big guys - Oakwrights, Carpenter, Welsh and Border have loads of experience with all sorts of configurations - so pick their brains.

 

You can probably go through planning without making a final choice of ‘cladding material’ - just the look and feel (and constraints imposed by the oak frame).

 

We live in a barn conversion currently and want to get the feel of raw oak (and other earthy materials) in the new build.

There definitely isn't much love is there haha! I think a lot of the big guy clients are paying the companies to do everything for them to be honest, we just were not prepared to pay what they were charging, and wanted much more input than they'd allow. I've not seen that insulation - will have a look. All Oak frames need skinning with something, we're just going down the ICF route rather than sips or bricks, that's the plan anyway... 

Luckily we have found some great SEs, but are doing all the design ourselves, so learning A LOT! The Oak supporting the roof is definitely the norm. 

We've got our planning already, with the final cladding material being half render and half clad, but we can always apply to change this if we want / need. 

Nothing better than the look, feel and smell of raw Oak. 

[Alan Ambrose]

>>> Yes, we are essentially building the house twice.

 

This gets trotted out fairly frequently on BH. So, conventional brick & block isn't? Something else covered with SIPs isn't? Yeah, don't worry about it if it works for you.

 

The other one usually raised is 'green oak expands contracts all over the place, how will you keep it airtight'?

 

Err, steel beams do this too, maybe steel doesn't have a great thermal expansion coefficient. Is this a problem in practice? So conventional softwood stick built doesn't move with moisture?

 

Green oak will move across its width but an irrelevant amount on length. It'll also settle down very quickly.

 

>>> We did speak to Oakwrights about it, but their costs were eye watering

 

FYI - I'm having sensible conversations with them re frame supply only. You can get a rough number for retail oak in £ / m^3 from online suppliers. (Last time I calculated it was £2.3K/m^3.) Then see how much the joint work and erection adds to the quoted price and check whether it's honest. I figure the oak frame guys should be charging about 3x the retail cost / m^2.

Edited February 3 by Alan Ambrose

[Iceverge]

6 hours ago, MCoops said:

We've had bifolds before (albeit the cheaper end of the market ones) but we weren't that impressed, so we are looking for either a french or patio door style I think - to be decided! 

 

Proper compression seals are key whatever you choose. Sliding seals don't work well . 

 

7 hours ago, MCoops said:

The render issue with woodfiber is interesting. The more we research it the more this comes up - it seems whilst the concrete inner itself doesn't track water, the woodcrete does absorb it while out in the elements during construction. And it's then difficult to get it to dry because we plaster and render etc, and it can't breathe, so the plaster and render fails - real pitfall for something that has legs. We'd batten before any render, and are also battening out the render / clad levels too. 

 

It's not solely a woodfiber issue. The houses I saw were EPS ICF. Amvic brand I think. 

 

Woodcrete is a different beast to woodfiber and I've never seen it in person. @JohnMo and @ToughButterCup have used it off the top of my head. 

 

In any case I would batten the ICF (before the pour to avoid drilling into concrete afterwards) and then fit cement board externally for to create a cavity for the rendered section. 

 

What's your plan for decorating inside the ICF? 

 

 

 

 

 

[JohnMo]

7 hours ago, MCoops said:

woodcrete does absorb it while out in the elements during construction

Not correct. Woodcrete is an open structure and water will free flow under gravity out the bottom. It doesn't readily absorb water.

 

7 hours ago, MCoops said:

And it's then difficult to get it to dry because we plaster and render etc, and it can't breathe, so the plaster and render fails

Not sure where you are getting the information but it nothing like anything I experienced doing our build. Are you really talking about woodcrete ICF blocks or something different? Or wood fibre insulation?