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Anyone built an extension with SIPs (Structural Insulated Panels)?

(16 Posts)
Crumbelina Sat 18-Mar-17 16:48:06

Bit niche!

We're hoping to build a double storey extension (9m x 5m kitchen on the ground floor and 4m x 5m on the first floor). We were originally going to use block and brick but we're now interested in using SIPs (instead of blocks) and then stock bricks for the outside. We realise that SIPs will cost more, but I think it'll be worth it.

We've sent out a request for quotes and already had a few rejections (not a big enough project for some companies and one has cited an access issue as we have a detatched house in SW London with a 1m side alley and they like to use a crane).

Does anyone have any experience with using SIPs, or any thoughts on them?

AgentProvocateur Sat 18-Mar-17 16:56:53

I've never heard of them being used for domestic buildings, but know they get specified a lot of larger scale structures.

ladypie21 Sat 18-Mar-17 17:00:00

I wouldn't have thought you would get the economy of scale on your extension for this to be practical. Plus you'd have an interface with the existing structure so not sure why you feel it may be worth it? If it's additional insulation properties you want you could go for extra insulation in a standard cavity build?

Crumbelina Sat 18-Mar-17 17:19:14

Thanks both. We did have a chat with one company last year at Grand Designs Live who said that it would (just about) make financial sense and gave an appropriate estimate of around £15k (although I'm sure the true cost would be higher).

We're going to be project managing the build ourselves (with DC2 due late September) and so we were swayed by SIPs because of the quicker build time, we'd be slightly less reliant on the trades and the SIPs company would be able to advise and help us with the structural drawings and building control.

This may all be wishful thinking!

Plockplock Sun 19-Mar-17 18:11:09

We have a single storey SIPs extension. I had reservations whereas DH was very enthusiastic. The panels themselves go up very quickly, so you have an actual roof and walls within days of the groundworks, etc. being finished. I was worried that they'd seem flimsy compared to brick, but I was thankfully wrong; insulation and sound wise, it's better than the rest of the house (Edwardian semi), in fact the SIPs extension has improved the warmth of the house as a whole. It has been 5 years since it was completed and we have no issues, but I do worry that it will be difficult to find easily find a builder to carry out works, should there be a problem...

Crumbelina Sun 19-Mar-17 19:57:10

Oh Plock, I think you've made my day! smile It's so good to hear from someone who has used them for a domestic extension. You must be so pleased that things went well and it's improved the warmth of the house. I'm not expecting miracles but I'm hoping they might help warm up our Victorian detached house which leaks like a sieve. smile

Can I be cheeky and ask a few questions please? Namely, what company you used, what size is your extension, what external materials you used (brick slips or something else?) and if you had any access issues during assembly, e.g. if the company needed to use a crane?

Sorry, that's lots of questions! blush

Plockplock Sun 19-Mar-17 20:43:30

I'm so glad that I've made your day, Crumbelina! Ours is 4m x 5m and is a covered in some sort of polymer render (my recollection is hazy) in white, which is water tight, breathes and never needs painting, apparently. I like the idea of brick slips; would you be able to match these to your existing bricks? We had no access issues as there is a passageway at the side of our house. The company we used are no longer trading, which causes me to wring my hands occasionally!

Crumbelina Sun 19-Mar-17 21:12:59

Wonderful - thanks so much for all the information! It gives me hope that we'll get some quotes in the next couple of weeks (was getting a bit worried as we got a few rejections and one company said that they would need to use a crane as opposed to our side alley and couldn't quote).

I like the idea of brick slips if we can match them to the London stock bricks we have. I just need to have a look at the sound proofing qualities as our gardens are quite small and it's a bit built up at the back so I don't want our neighbours hearing us and vice versa. As an alternative we might go with normal stock bricks as it could be less controversial with the council/building control.

I've been waiting for 2.5 years and counting for this extension so SIP assembly day will probably be the highlight of my year (oh dear smile).

Thanks again!

Plockplock Sun 19-Mar-17 21:39:14

I've stood outside knowing that the DC are making a terrible racket inside and whilst I can see their mouths moving, I cannot hear their screams grin.

It's amazing to go out in the morning and return home to find walls where there were none. I'd be surprised if they needed to use a crane, ours were just carried down the side passage. We spent quite a long time marvelling at the walls once the builders went home that day!

madeleinecreek Mon 20-Mar-17 08:18:38

My neighbour just finished using this company for a garden room (in sw London), using SIPs, might be worth chatting to them about extensions.

https://www.bespokesheen.co.uk/extensions

Crumbelina Mon 20-Mar-17 09:08:36

Thanks Plock! Definitely worth me investigating brick slips now if a render/SIPs give great sound insulation. One of the key conditions of permission from the council is matching the brick so I'll see if it's possible.

Madeleine, thank you so much for the link! They're pretty close to me so definitely worth me looking into it.

Sara107 Thu 03-Aug-17 22:18:11

Interested to know if you are going ahead with the SIPs Crumbelina? Sorry for arriving late and hijacking your thread! I'm interested in a SIPs extension. Like you we have access issues, there will be no cranes or heavy equipment involved!! We also, delightfully, have the neighborhood sewer flowing beside, and possibly under our site! I was wondering if a SIPs build would help get around that problem as it is a lighter construction so shouldn't need such extensive foundations, not sure if I'm right about that.

SocksRock Thu 03-Aug-17 22:23:22

sara if you are building within 3m of a sewer, you will need a build-over consent from the water company (Thames Water in my area). If the sewer is running parallel to the line of the foundation, it's going to be a tricky little problem for your structural engineer. SIPS are lighter than than traditional B&B but for a single storey domestic extension this probably won't make enough of a difference to affect the build over one way or another.

Crumbelina Thu 03-Aug-17 23:27:33

Ooh, didn't expect this thread to be raised again! I definitely have advice but have to go to bed as toddler loves a 6am wake up. Will update tomorrow. smile

Crumbelina Fri 04-Aug-17 07:28:14

Just coming back to this. We didn't go with SIPs in the end. Lots of companies refused to quote citing access issues for the large panels and a few wouldn't quote as the project was too small to be worthwhile. The few quotes we did get were very expensive (one was £80k+!).

We then moved on to Timber Frame and pretty much all companies we asked were able to quote. You can find contacts on the website of the Structural Timber Association. I'd recommend going for one that's relatively local (within an hour's drive) so they can come and do site visits, e.g. initial visit, check the foundations are ok for the frame etc.). In the end we can't even go for timber frame panels so it has to be stick build. That said, it means they can start earlier, are less reliant on the measurements being 100% correct and the build still goes up very quickly (1 day for the ground floor!). We're paying around £23k for a double storey extension of around 60 square metres. We commissioned the demolition and foundations from another company (£15k) and after the timber frame is complete we'll be using a brickie to do the external walls, tiler for the roof, window fitter for the sashes, sliding door company etc.

It's a lot of effort, learning and coordination as we're project managing it ourselves but we're in London and this build will cost just under £100k (with a high spec kitchen, appliances, slimline sliding doors, polished concrete floor, underfloor heating). If a builder had quoted for the lot then we'd be looking at over £200k I think!

Just wondering, what region are you in and is it single/double storey? Do you know how many square metres it will be?

Crumbelina Fri 04-Aug-17 07:31:36

Agree with socks - the foundations won't make much difference. We still needed them to be 1m deep for a light timber frame. We've just received a form from Thames Water re the sewer and need to look into it to see what kind of consent we need. Probably should have thought about it a bit earlier!

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