Insulating A Single Skin Brick Garage Workshop

[CrazyArsedMonkey]

Hello folks!

I am after some advice please. I have a detached single berth, single skin brick garage (or 1/2 brick width, as explained by @Lons in a similar thread), I have been using this as my workshop for the past 2 years.

I absolutely love being in my workshop, however, i need an Eskimo DNA transplant, or some insulation, as it gets chuffin' cold in there. I tend to lose myself in my work (keen hobbyist only), hence can easily be out there for 6 hours at a time, usually it is the cold that drives me in.

I have found several similar threads, but nothing that quite scratches my itch. For other's convenience, and to prove that i have done prior research, i have linked similar threads below:

Single Skin Brick Garage Workshop / Insulating A Detached Garage Workshop / Garage In Winter / Heating A Garage Workshop / Garage Workshop Advice

My workshop has an apex roof, terrible up and over garage door, double glazed window, composite door and concrete floor. It is rigged for electric with an Ed18 consumer unit, ring main and 16A socket. I think it is a pretty standard size, roughly 2.5m x 5m.

I will be making new doors which will be hinged at the sides, allowing toys machinery to be moved in and out on my own - i will make the doors thick, with some built in insulation. I am tempted to put gym style rubber mats down on the floor, providing some protection but would love to hear other ideas - especially ideas that have worked for other forum members!

As for the walls, i was thinking about 35mm studs with 50mm insulated plasterboard over the top, but would definately consider PIR insulation covered with OSB, i have no preference, i like both aesthetics. As i understand it, i need to leave a 50mm gap at the bottom to let the wall breathe (though this will let warm moist air from inside the workshop escape into the loft area...). I have also toyed with the idea of adhering 50mm insulated plasterboard direct to the walls, ensuring that i tape everywhere, preventing warm air getting to the wall (i read on a building forum that this was acceptable, and wouldn't lead to damp on the brick).

For the ceiling, i was simply going to use insulated plasterboard and engineer an air tight loft hatch (so i can store empty TStak cases etc up there). The soffits were changed 3 years ago, they provide insect protection and good ventilation, so i figure everything should stay dry up there.

If i use insulated plasterboard, i do not believe that i need to install a vapor barrier, but if using PIR/OSB, i would put a vapor barrier between the OSB and the insulation.

I want to minimise the amount i build the insulation out, as the workshop is already too small! I have considered external insulation, but feel this is too complex, costly and would look weird.

I am more than happy for people to throw spears or simply give advice / experiences - so please let me have it with both barrels

Any advice?

 

[Dynamite]

This situation is very similar to mine. I'm going to insulate the roof and the wood garage door properly but as for the walls... with it being not much distance between the internal brick walls, i cant afford to lose any from it as it just eats into the available space and its not wide enough as it stands. I realise its not insulation or good ventilation etc but I might consider screwing pallet wood direct to the brick(about12mm) but thats it.

Related post here... Workshop Roof Internal Insulation

Kind Regards...Rob

 

[Sachakins]

There is a good guide from kingspan on IWI here, about half way down.
https://www.kingspan.com/gb/en/know... solid brick,fixings and the surface skimmed.I've done this on a couple of mates garages, I used pre treated batons and a dpm roll, at 4 inch wide. They are warmer now,

I would consider not putting ceiling in, but insulate the apex roof instead.

You can still add truss shelving for storage.

I relaid an extra 200mm loft insulation over existing to give me 300mm, great for house, but it gets very cold up their now, and even well ventilated I had to change the cardboard storage boxes for plastic crates as you could feel them going soft with such cold for long spells over winter.

 

[CrazyArsedMonkey]

@Dynamite - very similar post, thanks for linking - i will have a read after work!

@Sachakins - I love the idea of insulating the top of the roof instead, but thought the trusses would act as thermal bridges, resulting in constant wet/dry leading to rotten timbers (in many years).

Do you reckon this will be an issue?

 

[Fitzroy]

The other threads you linked will discuss the technical details of different options so will not repeat here. Overall it's about choice and consequence.

The design standard best in class is brickwall, air gap ventilated externally, thick insulation, vapour barrier, internal lining. Each step you take away from this you increase the risk of problems ie condensation or poor thermal performance. However, you likely also reduce the cost and impact on the space available.

Another consideration is that the design standard is for managing a well heated and permanently occupied space. The lower the working temperature and the less the occupancy then the lower the moist air load the wall design has to cope with. A space run at 13-15degC, my ideal workshop temperature, and occupied a few hours a day by 1 person will have much less moisture to manage.

Your plan sounds sensible except one item. You say 'I need to leave a 50mm gap at the bottom to let the wall breathe (though this will let warm moist air from inside the workshop escape into the loft area...)' this suggests you are ventilating the gap to the inside envelope, which is precisely what you do not want to do. Any air gap on the cold side of the insulation is ventilated to the outside.

 

[CrazyArsedMonkey]

@Fitzroy - that makes more sense! I did realise it would be venting warm moist air to a cold area.

In my mind, the panacea is a warm wet box within a cold dry box - correct?

 

[Sachakins]

@Dynamite - very similar post, thanks for linking - i will have a read after work!

@Sachakins - I love the idea of insulating the top of the roof instead, but thought the trusses would act as thermal bridges, resulting in constant wet/dry leading to rotten timbers (in many years).

Do you reckon this will be an issue?

Treating the trusses first with the likes of Cuprinol would be my route.

Insulating at pitch needs a min 50mm air gap, face fixing insulation boards to truss face would be easiest, ensuring there is air flow from the soffit, also adding a couple of ridge vents will be beneficial.

The other thing to consider with insulation at eaves is that you have a bigger volumetric space to heat.

On one of the garages we fitted eaves insulation, just using 50mm celotex screwed and taped joints.
As eaves height was low, so all lighting could then be above eaves height. Handy for storing long timber lengths too.

Ended up adding a small ceiling fan to circulate the warm air back around the garage to maximise heat use a year are two later though.

A lot depends on how you want to use the void space, if it's for store and forget then ceiling is best. If it's constantly being accessed then a decent drop down loft ladder, the wood type is needed, but this takes up a lot of floor space to be kept clear in the garage itself.

 

[Fitzroy]

@Fitzroy - that makes more sense! I did realise it would be venting warm moist air to a cold area.

In my mind, the panacea is a warm wet box within a cold dry box - correct?

The panacea is a warm humidity controlled box within a structure that protects the warm box from the elements. A MVHR system exchanges air from outside the warm box to inside the warm box, taking away the moisture and returning the heat. This is how a passive house works.

 

[Ilya]

MVHR was exactly what I installed. Works really well, consumes very little energy (basically just a simple pair of ventilators at low speed)

 

[Ilya]

Ductwork and the unit in in the workshop loft

 

[Ilya]

Also, for the insulation itself, I did proper wall studs, pir insulation, soundproof plasterboard

The gate was the tricky part, but I managed to make it openable in case I need to move in out the machines