New Workshop

[Parm]

In the summer I have I will be constructing a new Worksop, it will be timber frame with ship lap on outside and ply lined inside.

I want to insulate the cavity, looking at the options I can use kingspan stuff (quite expensive) or the more traditional fibre glass stuff (not so expensive).

Question is am i gonna notice much difference between the different types versus the significant additional cost

 

[eSCHEn]

What thickness cavity mate?

 

[Parm]

Walls will be 100 MM and roof will be 150mm

 

[Parm]

Should have said its being done on the cheap as most materials have been supplied very cheap or free (good mates) so don't want to spend a huge amount on a insulation if I'm not going to see the benefit

 

[eSCHEn]

Personally at four inch thick I would be happy with glasswool. It can be a poo face to hang but those self adhesive spikes make life easier.

On the cheap? Rockwool or polystyrene slabs every time. You can pick up damaged polyurethane stuff now and again. Polystyrene can't be in contact with cables or it leaches plasticizer out of it

 

[Parm]

Personally at four inch thick I would be happy with glasswool. It can be a poo face to hang but those swlf adhesiv spikes

I have a plan, build timber frame and line internals, then place insulation between uprights and cover with breathable membrane before fixing shiplap

 

[eSCHEn]

Sounds like a good plan Parm

Mine is much the same except being a retrofit it's more annoying. I went with a non permeable DPM to line mine. I'm right in the line of fire for Atlantic storms so just stopping the water driving through its an effort.

 

[normspanners]

Went to a mates garage 12mx 13m 25mmthick the other day and he has had it foam sprayed cost £3500 though !!

 

[Parm]

Sounds like a good plan Parm

Mine is much the same except being a retrofit it's more annoying. I went with a non permeable DPM to line mine. I'm right in the line of fire for Atlantic storms so just stopping the water driving through its an effort.

Yeah I've seen your workshop, good job and n that. Did you do that yourself ?

 

[Parm]

Went to a mates garage 12mx 13m 25mmthick the other day and he has had it foam sprayed cost £3500 though !!

Nice but that's £3000 more than I'm spending on the whole build and that includes the concrete base

 

[cumbriasteve]

I had at my previous house a wooden workshop and I insulated the 75mm gap with rock wool, I always wondered however how much benefit it really was.

If I was trying to maintain a raised temperature 24/7 using heating then yes it would bound to be of some help, without heaters running though the workshop temperature soon matched the outdoor temperature, give or take a degree or two.

If I was building another I would probably just leave the air gap as it is, at least there is less chance of moisture being trapped and causing problems.

My present workshop has 150mm of insulation in the roof, that is a major help in summer, without it was like working under a grill on a hot day (steel sheeting)

 

[Parm]

I'm just trying to understand and evaluate the cost/benefit of kingspan. I see how it works on an extension with all the bells and whistles but can't get my head round the cost of it for a workshop vs the benefits it will bring.

Local builders merchant OBVIOUSLY reckons kingspan is the way forward but can't clearly demonstrate how

 

[WorkshopChris]

Last summer we built a shed with 50mm polystyrene between osb inside and out. Made a big difference, you can easily keep it warm in the winter with an oil filled radiator on low setting.

 

[Wendelspanswick]

Kingspan provides a physical barrier to draughts, especially if you tape the joints whereas wools need to be sealed in the cavity to be 100% effective so if using shiplap as the cladding you are right to use a vapour barrier.

 

[octo0072000]

you used to be able to get king span seconds from the factory by the load
seen some on ebay as well

http://www.ebay.co.uk/itm/Seconds-I...rm-/371609105441?_trksid=p2141725.m3641.l6368

 

[eSCHEn]

It's a 3m cube that I bought from the previous tenants. It's in reasonable shape but windows (2mm lexan) were UV knackered so I replaced with double glazing. I was going with polystyrene as it's just about identical thermally compared to glasswool and is nice and easy to handle. It has two main drawbacks though, flammability and the plasticizer problem.

 

[clift_d]

Kingspan has about 60% of the thermal conductivity of Rockwool - 0.022 vs 0.035, so you get a much better thermal performance in a thinner buildup. Generally the extra internal space you get by using a thinner insulation is worth more than the extra cost of the insulation so that is one of the big drivers for its use.

Whatever you choose don't forget the vapour control layer. I'd go timber frame with insulation between studs, with a vapour control layer on the inner face of the studs with any joints taped and then your internal lining, and then breather membrane and shiplap boards on the outside.

If you forget the vapour control layer you'll get interstitial condensation in your wall buildup.

 

[Parm]

Kingspan has about 60% of the thermal conductivity of Rockwool - 0.022 vs 0.035, so you get a much better thermal performance in a thinner buildup. Generally the extra internal space you get by using a thinner insulation is worth more than the extra cost of the insulation so that is one of the big drivers for its use.

Whatever you choose don't forget the vapour control layer. I'd go timber frame with insulation between studs, with a vapour control layer on the inner face of the studs with any joints taped and then your internal lining, and then breather membrane and shiplap boards on the outside.

If you forget the vapour control layer you'll get interstitial condensation in your wall buildup.

Ok that's interesting about the vapour control layer on the inside. What can I just use

Also planning to insulate the roof too with fibreglass then cover with 3mm ply, will this need vapour control layer too

 

[the snooper]

rockwool stops more sound then kingspan

 

[Parm]

rockwool stops more sound then kingspan

That's useful to know but noise isnt an issue as I live at the end of the village and only neighbors are sheep and lamas