Anyone built a SIPS garage?

[SonicHedgeHog]

We are seriously considering knocking down our old, cold and damp (in winter) garage and replacing it with one we can use all year round. I like the idea of SIPS panels because of their thermal efficiency, speed of assembly and the interesting open spaces you can create.

Has anyone built a SIPS garage. If so, do you have any advice and did you compare the cost with a more traditional construction method?

[V8RX7]

As mentioned in a previous thread - SIPS are pretty much the last thing to build a garage out of -they are expensive to meet strict thermal / air tightness regs - neither of which is required in a garage build.

[BoRED S2upid]

V8RX7 said:

As mentioned in a previous thread - SIPS are pretty much the last thing to build a garage out of -they are expensive to meet strict thermal / air tightness regs - neither of which is required in a garage build.

Depends what your keeping in your garage he may want a super fancy warm dry one to keep his pride and joy in.

How expensive are we talking per sq m?

[V8RX7]

BoRED S2upid said:

V8RX7 said:

As mentioned in a previous thread - SIPS are pretty much the last thing to build a garage out of -they are expensive to meet strict thermal / air tightness regs - neither of which is required in a garage build.

Depends what your keeping in your garage he may want a super fancy warm dry one to keep his pride and joy in.

How expensive are we talking per sq m?

Garages need ventilating... fire resistance is handy too

You can't beat brick / blockwork

[SonicHedgeHog]

Rather than calling it a garage, perhaps I should have called it a house for my car. I want airtight, warm and energy efficient. Windows and doors will be of a similar level of energy efficiency.

Not sure about the fire argument. I’m not going to be doing anything more flammable than I would do in the house and if my car decides to spontaneously combust a wooden roof will go up just as quickly as some SIPS panels.

I’ll try and find this other thread you mention. Sounds like there might be some good info there.

[Equus]

Bear in mind that even for the sort of fully insulated construction that would be applied to a new-build house, traditional masonry construction is cheapest, followed by timber frame, followed by SIPs.

So you need a coherent reason why to choose SIPs over other forms of construction, otherwise you're just squandering money unnecessarily.

The three usual reasons for SIPs (in rough order of importance) are:

• Airtightness: it is easier to achieve the extremely high levels of airtightness required by, say, the PassivHaus standard by using SIPs instead of TF or traditional. Unless you know where to buy an extremely airtight garage door (and after 30-odd year in the industry, I'm damned if I do), then you're pissing into the wind on this one (pun intentional).
• Thermal bridging: if designed correctly, SIPs are exceptional in this respect. But it doesn't become a significant factor unless you're working to PassivHaus or similar levels of insulation.
• Speed of build: maybe you have some pressing financial reason why you need the garage completed 3 weeks earlier at any cost. If not, see above.

If you can't justify the use of SIPs on one of the above criteria, then frankly its a gimmick for the sake of gimmickry.... and I say that as former Design & Tech. Director of a timber frame company that used to supply the stuff.

Also remember that one of the things that is usually beneficial in garages is the fixing of shelves. It's one of the things that SIPs is particularly useless at facilitating: it's crap at taking point loads unless you build in localised reinforcement (which then fks up the thermal bridging advantages, if you don't watch it).

[SonicHedgeHog]

Now that’s a good answer. Thank you. I wanted to reduce build time because I hate the mess. However, the downsides you mention outweigh the benefit of reducing the build time so I think I’ll have to go with cavity walls and some nice cladding.

As an aside, I think I have found some wooden bifold garage doors with built in insulation. I still need to check how well they’re sealed but given the price I reckon they’ll be ok. Oddly though, you’d think the bifold door companies would all offer insulated garage doors as well. Seems to me to be a straightforward extension of what they already offer.

[monkfish1]

Whats actually wrong with your old garage. You say its cold and damp, but why?

Unless its a complete disaster, you could just sort that out?

As Equus said, no such thing as an airtight garage door. On the garage on my old house, that was the weakpoint. But as it was the only air source, it just wasn't an issue in the real world. The garage ended up several times more thermally effiecent than the house!

For info, i did it as a steel frame and clad it. Pretty fast in the scheme of things.

[SonicHedgeHog]

The old garage is half single skin brick and half single skin timber with old crittle windows. Zero insulation. My wife has a little craft hobby room in the back. In the winter it is so cold and damp she has to stand next to an oil filled radiator and an electric fan. Even then it is often too cold and she has to come into the house to warm up. I can’t see how we can even begin to make it warn enough to use in the winter hence a completely new building.

[monkfish1]

SonicHedgeHog said:

The old garage is half single skin brick and half single skin timber with old crittle windows. Zero insulation. My wife has a little craft hobby room in the back. In the winter it is so cold and damp she has to stand next to an oil filled radiator and an electric fan. Even then it is often too cold and she has to come into the house to warm up. I can’t see how we can even begin to make it warn enough to use in the winter hence a completely new building.

Assuming its structurally ok, the insulation, lots of it.

Just finishing my big shed as i keep a lot of stuff i dont want rusty in it.4 inches of celotex all over except floor which was 1 inch with chipboard flooring over. With a dessicant de-humidifier in there, and no air leaks, it will keep itself several degrees above ambient and is easily heated.

Sure, new building would be nice and if the you have the money to throw at it, great. But it might not actually be necessary.

[V8RX7]

SonicHedgeHog said:

The old garage...

I can’t see how we can even begin to make it warn enough to use in the winter hence a completely new building.

That's easy - stick 50-100mm of celotex on the walls and roof.

The office I'm currently sat in I converted from an old garage - pretty standard stuff.

[SonicHedgeHog]

Very interesting. How did you get on through the winter? Was it not flippin’ freezing?

[V8RX7]

SonicHedgeHog said:

Very interesting. How did you get on through the winter? Was it not flippin’ freezing?

Bear in mind the insulation for houses has been slowly upgraded from solid brick, brick cavity block, brick 25mm poly insulation block, brick 50mm insulation block...

Even now most still use around 100mm rockwool which equals 50mm celotex.

50mm celotex is a huge difference compared to nothing.

I actually insulated most of my house with 25mm celotex under the floor (to sort out levels and a damp floor) 50mm on the walls and 150mm of rockwool in the ceiling (as it's cheaper and easier between joists)

Whilst it's not to current regs it's probably in the top 10% of UK homes for insulation

[mikevernon]

Interesting thread, but why are some people suggesting that SIPs are more expensive?

I want to replace my large brick garage before it falls down. It's single brick with occasional piers, a leaking cement/asbestos roof, very draughty wooden doors and a concrete floor without insulation. I've been quoted £47,000 for a 9m x 7m replacement with new insulated floor, Marley tiled roof and cavity block/brick construction. Sounds an awful lot for a garage so I'm looking at alternative construction methods, and SIPs look a lot cheaper to me for the basic structure, although I haven't yet found a local builder with sufficient experience.

The other problem is what to clad it with. Larch or cedar are expensive and not maintenance free, and steel panels look a bit agricultural. I could compromise with blocks and render, with brick pillars to break up the appearance,, but I'd like to hear a few more suggestions/opinions first.

[Equus]

mikevernon said:

Interesting thread, but why are some people suggesting that SIPs are more expensive?

Because they are, quite simply.

Make sue you're comparing apples with apples.

£47K for a basic garage of that size is on the expensive side, but that aside remember that the basic structure for a SIPs is just that: it's a basic structure.

You still need the foundations/ground floor slab, you still need the roof tiling, you still need the drainage, the door and the electrics. As you've already recognised you still need it cladding with something (either a separate masonry outer leaf or cladding on battens on breather membrane). Unless you're prepared to look at bare OSB on the inside, you need it lining with something internally, too.

At that size, you'll need Building Regulations, so you'll also need to deal with structural calculations (not usually necessary for a masonry garage, because they're covered by the Approved Document) and to deal with both structural integrity in fire and external surface spread of flame on the cladding.

By the time you've done all that, it will usually have cost a good bit more than a conventional brick construction.

[martin-g2gm3]

interesting,
I'm about to start a garage build in sips. 6x5.5m
So far the costs are as follows.
Base. £1500
Panels £2400.
Door £ 800. ( Roller shutter X 2)
Personal door and window £1250.
Cedral exterior cladding £2000.

Haven't decided on the roof yet. Either fake slate or fiberglass.( Not costed but estimate £1500.)
Interior will be clad in plasterboard for fire resistance ( not costed yet) plus electrics etc.

Even so this seems a lot cheaper than £40k plus quoted earlier?

[martin-g2gm3]

Forgot to mention. Sips are quick to put up and hopefully will afford the neighbours some degree of sound insulation as well as keeping me warm when working over winter.
😜

[sjg]

I’d set a watch on this thread because I was (and still am) interested in going this route - want some decent insulation both for controlling temperature and stopping noise from escaping. Interested in how you get on.

[Pheo]

martin-g2gm3 said:

interesting,
I'm about to start a garage build in sips. 6x5.5m
So far the costs are as follows.
Base. £1500
Panels £2400.
Door £ 800. ( Roller shutter X 2)
Personal door and window £1250.
Cedral exterior cladding £2000.

Haven't decided on the roof yet. Either fake slate or fiberglass.( Not costed but estimate £1500.)
Interior will be clad in plasterboard for fire resistance ( not costed yet) plus electrics etc.

Even so this seems a lot cheaper than £40k plus quoted earlier?

Don’t forget power, Equus talked about brick clad as well that would be significant £££. Obviously it’s possible to do cheaper

(I’ve just been looking at garden room about 6m by 3.5m, was about similar costs to what you mention. I planned to clad in corrugated iron as so much cheaper)

[V8RX7]

martin-g2gm3 said:

interesting,
I'm about to start a garage build in sips. 6x5.5m
So far the costs are as follows.
Base. £1500
Panels £2400.
Door £ 800. ( Roller shutter X 2)
Personal door and window £1250.
Cedral exterior cladding £2000.

Haven't decided on the roof yet. Either fake slate or fiberglass.( Not costed but estimate £1500.)
Interior will be clad in plasterboard for fire resistance ( not costed yet) plus electrics etc.

Even so this seems a lot cheaper than £40k plus quoted earlier?

I'd love to see the thought process behind SIPS and then cheap roller shutter doors.

I have them on mine - in summer they are two huge radiators, combined with SIPS - great as a sauna