Insulating part of garage for utility room

[danieljephcott]

Hello all,

Im just at the last stages of my house project and I just have the garage to sort.

As my garage wouldn’t be used for my car and the kitchen is tiny we thought it would be a good idea to split the garage in two and use one half as a utility room.

Now this is very much DIY and we want a good job but we are not expecting a proper heat tight room but we would like a utility that is warm in the winter.

Anyway I had already built the stud wall which has now been kitted out with electrics for plug sockets etc. we also have a hot and cold pipe for a little sink we are adding in. The ceiling on the utility side has all the pipework for the boiler as this is in the utility side of the garage and this also has electrics ready for spot lights once the ceiling has been boarded.

Heres a couple of pictures:

So you know, the side where the garage door is will be the garage part, the side where im standing to take the picture is the utility side.


Anyway I just want to ask some questions about what type of insulation to use. I was going to start with the stud wall. I was going to board the garage side and then have the electric boxes put in place and then put the insulation in from the utility side then finish by boarding the utility side up. What insulation is best. Ive seen 3 types, wool insulation, recycled plastic insulation or the insulation foam boarding. Which is best to use for the wall?

Next I wanted to start the ceiling, really it’s the same question, which type of insulation is best? I know I need to leave small gaps for the spot lights but when insulating the ceiling do I completely stuff the ceiling or do I need to leave a gap between the insulation and the wooden/felt roof?

Once ive done this ill see how the garage goes and see how warm it is, if its still cold I was then going to insulate the walls. From the picture the wall to the right is an internal wall as it connects to the next door neighbours garage but it’s a cold internal wall. The wall which is behind me is an outside wall and the wall to the left is an internal wall which is my lounge. The wall to the left I was going to just board with plasterboard that has that reflective foal stuff on it. as its an internal wall I thought I wouldn’t need proper insulation. The wall to the right and behind me I was going to batten and insulate then plasterboard, again im not sure what type of insulation is best to use.

Well this is the plan anyway, some advice and tips would be great and sorry for the long winded explanation.

Hope you can help

dan

 

[ban-all-sheds]

we thought it would be a good idea to split the garage in two and use one half as a utility room.

Have you checked that you still have permitted development rights for a conversion like that? If not, you'll need PP.

Now this is very much DIY and we want a good job but we are not expecting a proper heat tight room but we would like a utility that is warm in the winter.

Are you going to be heating it?

Anyway I had already built the stud wall which has now been kitted out with electrics for plug sockets etc.

Part P compliance via BS 7671?

Testing?


Re all the insulation, don't forget you'll need a vapour control layer over it, and you'll need to take care to keep the integrity of that when pipes. cables, electrical accessories etc are recessed. I would strongly advise against spotlights.

 

[ban-all-sheds]

Nice to see care taken when using a blowtorch.

The holes in that joist - what's their diameter in relation to the depth of the joist, and as a % of the span, how far are they from the nearest end?

 

[danieljephcott]

I didn't realise I needed planning. I'm just building an internal wall and one side will have some kitchen units and washer dryer in.

The electrics have all been done by an electrician.

I will be having a small rad in the utility part.

Can you explain the vapour barrier for the insulation.


What's wrong with spot lights. The spot lights that are being used are suitable for bathrooms, I thought this might be better.

 

[danieljephcott]

Nice to see care taken when using a blowtorch.

The holes in that joist - what's their diameter in relation to the depth of the joist, and as a % of the span, how far are they from the nearest end?

The holes I think are 25mm.

I'm not sure what you mean about the span?

 

[ban-all-sheds]

I didn't realise I needed planning.

You might, if permitted development rights have been removed. You should check.

I will be having a small rad in the utility part.

Then I think you'll need to achieve a minimum U-value performance for all the walls and ceiling.

Can you explain the vapour barrier for the insulation.

Warm space || insulation || cold surface.

If air gets through from the warm side to the cold you'll get condensation forming on the walls and roof timbers, leading to damp, mould, and with the roof, rotting timbers.

What's wrong with spot lights.

You need to cut holes in the vapour barrier.

The spot lights that are being used are suitable for bathrooms, I thought this might be better.

That means that spray etc can't get to the electrical connections - no guarantee that air can't get around or through the fitting.

 

[danieljephcott]

Ok so I now under stand what you mean. We could change the spots that's not an issue.

So can you get insulation that has this vapour barrier already?

So looking up the the ceiling I should see the plasterboard. Then the vapour barrier followed by the insulation and then some air space then the ceiling?

 

[danieljephcott]

Or do i buy some vapour barrier and secure it to the ceiling first and then add the insulation and then the plasterboard.

 

[danieljephcott]

ok so after all of the comments ive had a read up on things and have come up with the following.

for the ceiling i will just use a normal light and ditch the spots. its to much of a faff and this room is a utility in a garage not a nice decorated room.

so the plan is to use kingspan boarding as it has a foil vapour barrier installed. i will leave a 2 inch gap between the roof and the insulation. i will use insulation tape to cover any gaps or ripped insulation. i will have the insulation fit as tight as i can so it stays in place between the joists then i will use foam on any gaps.

then just plasterboard over this.

As far as im aware this should be suffient and shouldnt cause any issues with codensation etc.

please let me know you thoughts.

thank you

 

[Alastairreid]

i will leave a 2 inch gap between the roof and the insulation

You would then need to vent the gap between the insulation and deck.

Just full fill hard against the deck then do as you propose.

Is the garage attached to the house? if so you will need to apply for building regs.

 

[danieljephcott]

i will leave a 2 inch gap between the roof and the insulation

You would then need to vent the gap between the insulation and deck.

Just full fill hard against the deck then do as you propose.

so no gap at all just basically buy kingspan insulation thick enough to fill the whole gap from ceiling to plasterboard.

 

[Alastairreid]

Yes! The idea is to leave no voids for moist air to condense.

Pay particular attention to your vcl tape all joints, silicone the perimeter and foam any gaps you may have in the insulation.

 

[masona]

The holes I think are 25mm.

I'm not sure what you mean about the span?

The most common are 22mm pipe and I guessing you have 10mm clearance all round so maybe 42mm dia hole?

 

[ban-all-sheds]

Or do i buy some vapour barrier and secure it to the ceiling first and then add the insulation and then the plasterboard.

It needs to be on the warm side.

 

[ban-all-sheds]

So can you get insulation that has this vapour barrier already?

Yes.

Or you can use stuff without and foil-backed plasterboard.