Is it worth insulating a workshop for 2 evenings a week?

[frugal]

There have been lots of threads about how to insulate your workshop. If I was to do my garage I would need 34 sheets of 2400x1200 kingspan 50mm to do ceiling, walls, door and floor.

Even if I snap up some of the seconds that are available online that is still £350 plus about the same amount again for OSB to cover it, and I will need to do something with the windows.

Given that I get out there 2 evenings a week, is it really worth it, or should I just stick with my little fan heater and put sheets over the machinery if I think it is going to be damp outside?

 

[Dibs-h]

There have been lots of threads about how to insulate your workshop. If I was to do my garage I would need 34 sheets of 2400x1200 kingspan 50mm to do ceiling, walls, door and floor.

Even if I snap up some of the seconds that are available online that is still £350 plus about the same amount again for OSB to cover it, and I will need to do something with the windows.

Given that I get out there 2 evenings a week, is it really worth it, or should I just stick with my little fan heater and put sheets over the machinery if I think it is going to be damp outside?

Why not use Rockwool for the walls & roof - got to be cheaper!

 

[wizer]

I suppose the questions you need to answer are: How much does the heater cost to run each year? How much of that will you save by insulating? How long you intend to be at that property. Is it an attached garage? If so, will the insulation also help with the house?

 

[frugal]

Why not use Rockwool for the walls & roof - got to be cheaper!

I have a pitched roof on the garage. I would put the insulation on the pitched part itself rather than put down floorboards and create an attic like affair. The beams are 100mm deep. As everything I have read states that you need to keep 50mm above the insulation for ventilation, that means that the insulation in the roof can only be 50mm thick. the thinnest I have seen rockwool is 100mm, which is why I was looking to use Kingspan.

Likewise for the walls, I can stand to loose 2x(50+11)=122mm off of the width of the garage by using 50mm stuff, but using rockwool in the walls would loose a lot more (and I would need to put up 100mm battening to attach the covering to).

Or have I got it wrong, is there a cheap way of putting in insulation using rockwool?

Basically the things I looked at are:

- Rockwool - Too thick

- Insulation slab 50mm - £4.17 sq m

- Kingspan 50mm - £3.60 sq m if you get the right bargain.

 

[frugal]

I suppose the questions you need to answer are: How much does the heater cost to run each year? How much of that will you save by insulating? How long you intend to be at that property. Is it an attached garage? If so, will the insulation also help with the house?

In Order:

1kwh heater 6 hours a week = 33p/wk and it only gets used when < 10C

It would probably save most of that cost as the garage would get down to ambient temperature between sessions, but will probably not be needed if the place was insulated.

We are planning to stay here for a long time.

It is a stand alone building 3m away from the house.


Does the insulation help with any damp air / rusting problems by itself, or does it only gain that property when the building is kept up to a certain temperature? I.e. is this only going to be any use at all if I keep an oil fired radiator on a thermostat all of the time?

 

[motownmartin]

It is a stand alone building 3m away from the house.


Does the insulation help with any damp air / rusting problems by itself, or does it only gain that property when the building is kept up to a certain temperature? I.e. is this only going to be any use at all if I keep an oil fired radiator on a thermostat all of the time?

When I first built my small workshop/Large shed I got a lot of condensation forming on my PT and Bandsaw, this seemed to happen when it was cold outside and the sun warmed up the shop, which created a lot of rust, this was until I fitted some 40mm foil faced kingspan and some loft boarding on the floor, now it all seems to be fine 6 months later.

I think what happened was the sun warmed up the damp shed walls making the air high in humidity, I might even fix polythene sheetingand hardboard or just OSB.

I plan to do another, bigger workshop in a couple of years, to set me up for retirement.

 

[Nev Hallam]

I have a double garage workshop, I have studded the walls and used 75mm kingspan inbtween the studs, the ceiling I nogged out between steel 'L' beams using CLS 3x2 insulated between with rockwool and skinned the lot in plasterboard. I had issues with old garage door margins and such but I since then I obtained a storage heater which I plan to use.
Had issues with my cast machine beds rusting over through winter but nothing machine wax hasn't sorted, I plan to fix any issues before next winter.

Don't spend £350 buy cheap or obtain for free!

 

[OPJ]

If you're worried about spending too much money then I think you should look at draught-proofing, first of all. Sealing any gaps around the main door, window(s) and around the eaves where the roofing sheets meet the wall plates on top of the walls (expanding foam is great for this) - that should make some difference.

Before he left, Mike Garnham told me that with corrugated roofing sheets, a 1in/25mm gap is fine - meaning that, with 100mm/4in rafters, you could even have 3in/75mm insulation. I'd clad the roof with white melamine-hardboard, personally. It's cheaper and weighs less than OSB. Though I'd still use oriented strand board on the inner walls.

What about putting in a floor over heard and creating a small storage area in the pitched roof? That could also help to keep the heat in below.

You may still find that after plugging all the gaps and insulating the building, you still have a condensation/rust due to a lack of ventilation (in which case, you'd need to fit a couple of vents).

 

[OLD]

The insulation on the floor is low priority just chip board is fine, also some savings can be made using expanded polystyrene with 11mm osb over in the walls use the good stuff in the roof or modify the ceiling as above .

 

[dickm]

My take on this would be to do all the insulation you possibly can if you intend to stay there a long time. Heating costs will only go one way - UP. And the more uniform you can keep the temperature in the shop, the better your tools and your work will like it.
Worth keeping an eye on local papers/free-ad mags/ Freecycle for insulation - there's always someone who's bought a sheet/roll too many and wants to get a bit back for them.

 

[Boz62]

You can get rockwool in 50mm and 75mm "insulation batts" - it's normally used for cavity insulation. Wickes stock it, and many other places. It is a very dense rockwool, so it also better for sound insulation than Kingspan, although not quite as good as thermally, but a lot cheaper. The batts are also easier to handle than the rockwool rolls as they are firmer, so they cut and fit tightly really easily. I used 50mm in the walls and 75mm in the roof with a 6mm ply ceiling.

Another thought - do you HAVE to insulate the whole garage? I've insulated about 1/3 at one end, with a partition wall and large door (50mm rockwool inside both) in between. So the insulated area is my handtool, workbench and power tool area with a fan heater to keep it warm. The "cold" end is used for cutting up sheet material, storage and more occasional large assembly jobs. I spend much more time in the warm end, particularly in the winter . Works for me as an occasional user.

Boz

 

[studders]

Why not use Rockwool for the walls & roof - got to be cheaper!

Or have I got it wrong, is there a cheap way of putting in insulation using rockwool?

You can get the Rockwool Slabs in 25-30mm thickness for about £2 or £3 sq metre. Obviously the thicker 50mm would be more efficient though.
Myself, I'd just do the ceiling first and see how that goes. I reckon it would cut down your heating costs significantly.