Garage/Workshop Winter-fication

View from the side door which is the main one used. You can see the new(ish) plastic roller door that seems to fit smoothly without air leaking in around the sides or bottom as the old one did.

This is the view from the big door which shows the dingle glazed window and small door. You can also see the pipe where hot air is pumped in by the diesel heater. This is clean air without any diesel fumes as basically it just sucks fresh air around the engine where it heats up and this heated air is pumped in.

This shows the rafters. The existing white wood ceiling was put in a few years ago to reduce drafts but mostly to reflect light and make the garage less of a black hole. I plan to re-use some of the short white planks to hold up the polystyrene. Basically put a long screw thought the plank, the insulation board and into the rafters. The short plank with then act like a really big washer to support the polystyrene without too much localised pressure.

That is going to take some effort and cost to do 'properly'.

I rented a house with similar single block wall and wood roof garage - and someone had tried half heartedly to insulate it. It dripped with moisture and damp...

Can you do something on the roof? Slapping 100mm of foam and then a new waterproof membrane is likely a quicker, cheaper and simpler option for the roof....and maybe avoid some damp issues?

I would say yes to the ins. boards between the rafters.

But if you are going to go mad and expanding foam all the joints etc to try and seal the heat in as much as you can, you may need to add some ventilation, air brick, trickle vents on windows etc.

Should make a good bit of difference though, in just retaining the heat created, rather than turning it into a sauna

 I plan to build a Carbon Fibre car over the winter

sloblocks to the insulation - tell us about this

I agree with Moab, tricky to do well and avoid condensation issues.

What temp do you need to cure resin successfully? And can you realistically maintain that?

I was thinking insulation board BELOW the rafters. I can lose 50mm of height for the easy of just banging the polystyrene up.

Possibly not the greatest design diagram but hopefully understandable. The boards rest against the rafters. There are then small planks screwed through the insulation and into the rafters to hold them in place. If I need tpo remove a board in the future I unscrew the planks in the middle and then loosen and rotate the ones at the edge keeping it close to the neighbouring board.

Seems the quickest and easiest way. I just need to mark up where the rafters are and use some of my 100mm screws.

[i]I agree with Moab, tricky to do well and avoid condensation issues.[/i] - The only source of heat into the garage is the hot dry air from the heater plus anything the machines give off. I suspect this might still be an issue but if it is then perhaps some strategically placed vents will help. The reduction in cold wet air entering the garage will also help.

[i]What temp do you need to cure resin successfully? And can you realistically maintain that?[/i] - The resin wants about 20C to cure but I can build smaller enclosed boxes for those if required. Having the garage warmer than ambient winter temperature just makes everything easier though as all the materials prefer to be warm rather than near 0C, as do I.

[i]sloblocks to the insulation – tell us about this[/i]

One car now sold which should fund the purchase of a 911, hopefully in the next few weeks. The big delay in selling any cars has pushed this back from a summer to a winter project, hence the need to insulate the garage.

you're going to weld half a 911 to a half of a DS and then mould a carbon fibre shell to cover the result to make an actual factual drivable car?

Citroen Carrera? Sounds cool 😎

Porsche Diane?

Thread hijack sorry.....in a similar situation. My garage has big er metal joists and the roof is about a foot above the bottom of the joists so I was thinking of making a false ceiling with whatever sort of insulated board is correct. This would still leave the ~foot of air gap above it for ventilation, maybe ok?

Is it worth boarding the vertical walls inside with insulated boards? Looks like we both have breeze block although mine externally is 'normal' bricks, no idea if there is a gap between them and the breeze blocks

I appreciate this is one of those 3rd world issues or whatever the phrase is but after buying my first house (due to the large garage hah) in my early 40's it would be nice to be able to use it more. Currently 9 months of the year it's too hot or cold. I'm not looking for miracles or making it like the house, just a bit cooler in summer and more importantly warmer in winter when it is normally only a couple of degrees above outside temperature

thanks

As youve you have guessed, you need to be careful if you fill the joist void with insulation, there must be an air gap.  Otherwise the heat exchange contestation rots the joists and possibly causes condensation inside. Your foam board on top of the rafter looks to maintain the air gap? so should be good.

I plan to leave lots of air flow and ventilation ABOVE the insulation boards from the gaps between roof tiles and the tops of the walls. The main body of the garage below the insulation will have the warm dry air from the heater plus what leaks through the little door and single glazed windows. Hopefully this wiil prevent damp.

dlr - insulation only does anything useful if there is a heat difference either side of it. Unless you are adding heat inside the garage, adding insulation will do little. Without heat, drafts and wind gaps are your problem. Just putting the wooden slats on mu joists made a big difference to this. Now I have got a cheap heater I am putting heat into the garage so I want insulation as well.

Car project = Porc-chop? Citrwrong?
Not planning of grafting a DS front end on, that would be silly and doesn't fit in any dimension (I did check). I am planning on removing the body panels from the 911 and creating ne ones over the inner structure. Easy 🙂

100mm screws?

10mm through the plank, 20mm into the joist.... What thickness is your insulation?

I'd def foam the gaps.... Makes a big difference.

50mm insulation board probably, + 10mm for plank so yes, I could probably get away with some 80mm but I have a big box of 100mm screws

WCA: Yer I need to sort my drafty door. I do have a heater I turn on when in there in the winter so if I can then minimise heat loss through the roof like you that should help. Just wondering if worth putting something on the walls as well

PS: Citroen's great, had tons, never a DS though

Looking forward to the offside 911, nearside DS half and half!

I'm also in the process of looking at insulating / making less manky a slightly more modest garage. I replaced the roof with wool backed agri box profile sheeting about ten years ago when we moved in. The wool back should, in theory, help manage condensation. There's decent airflow through the sides. I know this because of the draughts and because of the wisteria that's invaded the roof space.

There is airflow through the taller bits of the agri sheet, so I'm thinking of insulating between the overbuilt 200mm joists installed very 18" and then putting a thin insulation skin over the lot. Haven't got as far as thinking about the walls, floor or doors yet.

The problem is that I've described a cold deck roof - something that doesn't meet Scottish building regs and is actively discouraged in England (I'm down south) - the big problem with cold deck is generally condensation.

This is going to get expensive, isn't it?

Car project = Porc-chop? Citrwrong?

Carrafari?

I am planning on removing the body panels from the 911 and creating ne ones over the inner structure

You what?????? BURN HIM🤬

.....Oh hang on I'm logged into STW not Pistonheads.

Will you be able to stand a 29er upright in the back?

[i]BURN HIM🤬

…..Oh hang on I’m logged into STW not Pistonheads.[/i]

Okay it is likely to be a Carrera 4S BUT it is also likely to be Tiptronic and probably cabriolet so BURN IT is a more likely PistonHeads reaction.

I am looking forward to a drive down to Stuttgart via Paris in it though. Here are two different computer mock ups by other people too scared to turn a much loved and great car into an briefly interesting piece of motive art

Following this thread with interest as I also have a garage which is freezing, even though the rest of the house is warm.

Looking forward to seeing how you sort this.

I'm also in a similar boat, garage is 6m x 4m, same construction. Detached.

It gets an awful lot of damp / condensation on stuff I have in there in Autumn and Spring (the repeated changing temperature and free-flowing air in/out c/o the roof.

A mate improved his a bit by cutting polystyrene to fit his main up+over door really well then a  panel on top - that was a big heat sink.

I'm thinking a fibreglass./ resin main door with insulation.may help.  But maybe I boarding and insulating the rafters would help (I have stuff stored in the rafters.like kayak paddles, suit cases etc)

I insulated mine as I built it so it was a bit easier. It's single skin block built. The walls are internally insulated with either 50mm celotex or 100mm rockwool depending on what I could get hold of and whether there were pillars. Then lined with OSB (reclaimed from building site hoarding). The roof is a warm deck with 80mm celotex. Warm deck is a much better option but can't really be retrofitted without a lot of effort.

I wouldn't be keen on polystyrene inside especially if welding and grinding. Celotex would be better or rockwool between the rafters and plasterboard or timber to cover it.

Note that kingspan and celotex (phenolic foams) are about twice as insulating per thickness. I'd use these rather than polystyrene with filled and taped joints. If you're concerned about fire risk extend your rafters downwards and put Rockwool between. Glass fibres are very difficult to set fire.

Might check out 25mm of better insulation and tape the joints then. It will be a lot easier to fit and I can still bang stuff into the rafters through 25mm much more easily than 50mm. It doesn't really need to be that well insulated I suppose

Just checking and I reckon the polyurethane insulation boards might be a good bet as I will need some of that to sculpt the buck for the DS911 panels