New Member from Cork Ireland building ICF House

[Blynchy]

Hello there,

 

Came upon this website trying to do some research for my new build. I still have a lot of items in the air and I'm trying to gain some clarity. Starting my new build in the coming months and the only thing I have nailed down is that the construction will be ICF. I'm also strongly considering constructing the roof from 250mm EPS Panels supplied by Thermohouse. Has anyone used these or similar and how did you get on? 

 

As I mentioned I'm trying to gather information on everything from solar PV, to heating systems for hot water and space heating to window sill details. From my brief look at some of the posts, it appears that you are a knowledgeable bunch. I'm looking forward to delving in deeper and adding where I can

[Gus Potter]

1 hour ago, Blynchy said:

Hello there,

 

Came upon this website trying to do some research for my new build. I still have a lot of items in the air and I'm trying to gain some clarity. Starting my new build in the coming months and the only thing I have nailed down is that the construction will be ICF. I'm also strongly considering constructing the roof from 250mm EPS Panels supplied by Thermohouse. Has anyone used these or similar and how did you get on? 

 

As I mentioned I'm trying to gather information on everything from solar PV, to heating systems for hot water and space heating to window sill details. From my brief look at some of the posts, it appears that you are a knowledgeable bunch. I'm looking forward to delving in deeper and adding where I can

Hi Blynchy.

 

BH is a huge resource. It's stunning how much real practical info is here.  There is a great mix of folk here. You'll always learn something here. I do each time I visit.

 

Sounds like you are starting out on a journey. Best thing to do is to try and get familiar with the search function on BH..it's not google.. not commercial (so far) so you can find some really eclectic and valuable stuff. You'll need to spend a bit of time raking about but in doing so you'll pick up info on a pile of stuff and the next steps once you get moving on the build.

 

A bit of time spent here will probably save you a fortune. Don't forget that building something yourself should be fun too.

 

All the best.

 

 

 

 

 

 

 

 

 

[PaddyP]

Hi Blynchy, I'm in Ireland myself and building with Amvic ICF and Thermoroof panels are being delivered this morning. Can definitely recommend the KORE insulated raft and Amvic ICF. Will let you know how the Thermoroof goes! 

[Conor]

We recently put on thermohouse roof panels. A few points.

 

A fast installation and good value if you have a simple roof. Gordon from thermalshell construction did an excellent job. Dormers, valleys etc really add to the install time and cost as there is a fair bit of wastage. Ours took just over a week. Cost was about the same as a cut roof.

 

They are not entirely waterproof when done. We still had loads of water seeping through at abutments and valleys. So you still need your roof fully finished before starting second fixes.

 

A fair bit of additional joinery required - soffits and facias need to be built out, more so than on a timber roof. By far the biggest pain is all the counter battening. Needed on the top of the roof to take the roofing lath. I had 900m to do.

 

But by far the biggest issue is on the underside. If you are going for vaulted ceilings or fixing anything to the underside of the panels, it's a massive, expensive pain. If you are boarding, you need to batten at 400mm centres. Grounds for electrics are also required. There's nowhere to run cables. You need to use 180mm long harden steel screws (timpco velocity) to fix through to the steel channels. They are £45 for a box of 100. We got away with a cheaper alternative at £30 but we're harder to drive in.

 

All in, I'd say there's at least an extra week of joinery work and its cost me in the region of £3k so far, and that was me battening the roof myself, saving £2k.

 

There are other issues. We couldn't install our SVP as couldn't get a tile vent that would fit between the steel channels- but I'm sure we could have found one that worked, just not in the time we had.

 

We had to install a structural bracing "collar ladder" as we slightly exceeded and measly 3.5m max span. Alternative would be purlins, but wasn't an option for us due to head height issues.

 

U value of 0.15 isn't amazing and it wouldn't be easy to add extra to the underside.

 

All of those things take away a lot advantages over a traditional roof, you're not really saving any time or money by not needing to put in insulation and airtightness. And it costs a bit more. That said, if you have a good joiner lined up and the materials, it's still a faster job than a timber roof and once it's done, it's done. No worrying.about finding insulation, somebody to fit it, all that expensive airtightness work.

 

If you are doing a simple roof with no dormers ,valleys etc and the roof will be entirely attic space, then I'd consider it. For anything else, I think it's less attractive.

[jack]

17 hours ago, Gus Potter said:

Sounds like you are starting out on a journey. Best thing to do is to try and get familiar with the search function on BH..it's not google..

 

Yes, the standard search is a bit ordinary. However, it's easy enough to use google's functionality. Just put together whatever search term you're interested in and add the word "Buildhub". There's a more formal way (add the following to your search: site:buildhub.org.uk) but it isn't necessary.

 

17 hours ago, Gus Potter said:

... not commercial (so far)

 

It will never be commercial while I or any of the other people currently involved with the site are running it. The original founders unanimously agreed that we would be completely non-commercial. No-one is paid anything for their work. There are no sponsors and no advertising - not even Google ads on the landing page.

 

The quid pro quo for this freedom from advertising is our occasional request for voluntary donations from members. That's running at the moment (look for the floating message at the top of the screen), so if anyone reading this has found the site valuable and has a few bob they can spare, feel free to send it our way.

 

Maybe send 5% of whatever money we've saved you!  

[Iceverge]

@Blynchy

 

Welcome welcome. 

 

We're not too far from you being in the rebel county also. We've been in 6 months now. Passive house with strip foundations, wide cavity walls and trussed roof. 

 

Any plans you'd care to share?

[Blynchy]

16 hours ago, PaddyP said:

Hi Blynchy, I'm in Ireland myself and building with Amvic ICF and Thermoroof panels are being delivered this morning. Can definitely recommend the KORE insulated raft and Amvic ICF. Will let you know how the Thermoroof goes! 

I am looking at the Amvic system myself. I haven't fully decided on Thermohouse yet. My one gripe is that the internal leaf is only 50mm. This leaves very little roof for a window board. The flip side is that I always believed it was better to have more insulation on the outside so once the building heated up it would retain the heat for longer but I could be very wrong in that assumption as the gains might be minimal. I am also in another conversation with a separate builder who will only use Altherm. I guess everyone has their own preference. 

 

Like you I think the Kore foundation slab is a excellent idea, In my case I didn't need deep footings so doing a cost analysis proved it was cheaper to go with strip foundation and a 75mm subfloor. Im then going to put in 180mm KORE silver and finished with a 70mm screed. Some areas will be 50mm where I'm putting in a timber floor.

 

I would very much appreciate an update on the roof. Thank you

[Gus Potter]

On 26/08/2021 at 19:06, jack said:

 

Yes, the standard search is a bit ordinary. However, it's easy enough to use google's functionality. Just put together whatever search term you're interested in and add the word "Buildhub". There's a more formal way (add the following to your search: site:buildhub.org.uk) but it isn't necessary.

 

 

It will never be commercial while I or any of the other people currently involved with the site are running it. The original founders unanimously agreed that we would be completely non-commercial. No-one is paid anything for their work. There are no sponsors and no advertising - not even Google ads on the landing page.

 

The quid pro quo for this freedom from advertising is our occasional request for voluntary donations from members. That's running at the moment (look for the floating message at the top of the screen), so if anyone reading this has found the site valuable and has a few bob they can spare, feel free to send it our way.

 

Maybe send 5% of whatever money we've saved you!  

Jack.

 

"It will never be commercial while I or any of the other people currently involved with the site are running it."

 

Delighted to read this.

 

Is there any merit in letting folk know what you need in funds + moral support + members own time to keep BH sustained? Yes BH have gone Ltd but I can understand what might drive that..

 

If you look back on the history of BH it seems to me like it started with a few  enthusiasts all wanting to share knowledge. It caught on in a pretty big way. These founder members have put in a huge amount of work. I think to myself.. how is this to be sustained in the long term.

 

It would be a sad loss if this body of knowledge and annecdotal evidence of folk building / renovating etc their own homes was to be lost. It is in fact a historical record!

 

It would also be a disservice, not least, to some of the founder members that have been lost or just moved on if BH were to fall.

 

Jack.. yes the advice on BH must have saved folk a fortune at times.. so 5% is a good ask! .. you won't get that quality of advice elsewhere for free.

 

I ask.. how may we help?

 

 

 

[jack]

Thanks for the kind words @Gus Potter, they mean a lot to us. Thanks also for your own contributions, which are exactly the sort of helpful, unbiased information for which people come to BuildHub.

 

Yes, there was a lot of work early on, and certainly there's ongoing effort to keep things running, but it's largely settled down so that it doesn't take up huge amounts of anyone's time. We've put reasonably robust systems in place to keep out spammers, and the odd one that squeaks through gets the immediate ban hammer. Admin is taken care of by a small group who have occasional online meetings. 

 

Because no-one is paid, we have modest financial needs: software licensing, site hosting, the costs of running the BuildHub company - that sort of thing.

 

Probably the main thing we could do with is help on is the technical side. We have some great people helping us out with our IT needs, but having another experienced person or two to fall back on would be helpful, particularly if they have experience with the forum software we use.

 

I'm not too concerned about the long-term viability of the forum. The admin and mod team has been pretty consistent for a long time. If/when we get to the point where people started drifting away, we'll try and recruit from existing members. 

[ConorB]

Hi all, hoping to drag this topic open again! 

 

About to start self building an ICF house with raft foundation. Looking at using the Castleform wall & raft systems and am fairly happy with my choice there. For the roof though, I'm finding it hard to pick between the Thermohouse panels and a standard pre-framed truss roof.

 

Has anybody ran the figures and got a cost comparison for finishing out a warm roof space? Based in Ireland. House design relatively simple T-shaped plan with a flat roof joining 2 A-roofs. One A-roof single story vaulted and the other a standard 2story. 

 

Any advice is greatly appreciated!

 

Conor

 

[Iceverge]

Hi @ConorB Welcome. 

 

It does depend on what you need. Unfortunately it's a piece of string question so maybe you could narrow it down!. 

 

Do you have a sketch or plans for your roof?

What are your airtight requirements?

How available are good carpenters? 

Is noise lightly to be a factor? 

What are your planned roof coverings? 

What U-Value is needed? 

Are you on an area that gets prolonged heat waves? 

 

 

[ConorB]

The two roofs are pretty simple A-Framed gable roofs. Airtightness I suppose would be achieved with membrane wrapping around the perimeter down onto the inner leaf ICF wall. Good carpenters are hard to come by but I do have a friend in mind who I think would be happy to put up a standard trussed roof for me. Noise is not an issue and as I'm in Ireland, heat waves are fairly uncommon! 

 

Not easy to make a decision for sure. Think I'm leaning towards a pre-made truss with a simpler cold roof detail. The attic space is not going to be used for anything other than storage so reckon might make more sense for cost reasons to go that route.   

[Iceverge]

Sorry I missed your post. Maybe use the quote function or the @ to tag me. 

 

We're in Ireland too. Passive standard build. Moved in in 2021. 

 

We used a raised Heal trussed roof,

 

 

We have a cold loft with 450mm blown cellulose. It's a sealed roof as per the Tyvek manual with ventilation over the membrane via battens and counter battens. 

 

We stapled and taped an airtighess membrane under the trusses and returned it to the inner leaf of plaster on the external walls. The membrane oversailed all inner walls to minimise risk of leakage. We used two layers of 44*47mm battens under the membrane to run our MVHR pipes and wires. Then a layer of standard plasterboard and skim. We had only 5 wires into the attic. I used a small square of ply instead of the membrane and I drilled one hole for each wire and sealed with airtight sealant. 

 

I bought an airtight attic hatch too but nothing gets stored up there. 

 

Time over again I would change 2 things

 

First use just a single layer of 20x70mm battens for the wires only.  Then run the MVHR in the attic, it'd be much easier and as I was doing the airtightness I could be confident I'd have sealed them properly. 

 

Second use a double layer of plasterboard. The house is so quiet that we can hear the wind through the 450mm cellulose. Either that or a layer of 11mm OSB as sarking, it'd stop the membrane flapping too. Or maybe both.