Insulating Concrete Shed

Saruman

I'm getting a pre-fab concrete shed (10x20) installed at the moment. It has two PVC double glazed windows. I will be putting in a PVC door too.

I want to insulate it and basically make it in to a gym/brewery.

What would people suggest as the best way to do the walls/ceiling? The floor is easy enough.

The inside looks something like this.

I would like the end result to be something like this.

I know from this thread that I can get decent insulated plasterboard at a pretty good price but what's polyiso? What would be the best way of doing it?
A simple way would be to put in a wooden frame, tape up the foil bubble wrap stuff and then insulated plasterboard over the frame. Something like this video.

Any thoughts?

I will also be running electrics but that should be straight forward. I plan to put in the sockets and wires, consumer unit, run an armoured cable to the main house consumer unit. Leave it all disconnected and get an electrician to patch it all up and make sure it's ok.

Saruman

I know that no one has commented yet but here's what I'm doing.

The shed is installed. Here's a pic of the inside.

I worked out that I need 19 boards of 8x4 drywall for the inside. I went for 52mm platinum plasterboard. I understand that I can use the dot and dab technique to fix them to the concrete walls. That should be simple enough.

It's the ceiling that I am worried about. They are big heavy boards. At first I was going to lay insulation (fibreglass type stuff) and then screw in the boards but I'm not sure that screws would hold it.

Looking at the picture, what would people think about this. There's a sort of a shelf at the start of the roof which the joists are sitting on top. I was thinking I could mount the boards in between the joists, sitting it on top of that shelf and then I can screw some timber in to keep them in place.
It wouldn't be perfect but it would be better than nothing. One would be working out in the gym so as long as it retains some heat, it will be ok in the winter.

Really, I just want to get the gym set up as soon as I can on a budget that is now starting to go over. As long as there are no short term issues. I can always revisit some things at a later date when I have more money to spend.

Any comments? Suggestions?

fear corcaigh

I'm not sure how putting the insulated slabs straight onto the solid walls would work with dampness coming in, no cavity to help prevent it.
I did something similar a few years ago for a guy. He had a solid block on flat wall and we put treated 2*2 batons with a layer of damp coarse behind on the wall. 50mm slabs were screwed onto walls and ceilings.

There is no problem putting these slabs on the ceilings, I've done it numerous times including my own dormer bungalow, just put enough screws in them and they will be solid out. The hard part is getting the first one in place correctly, its easy after that, just need enough help for lifting.

Where the walls meet the ceilings looks a little awkward because of the height of the windows. You may need to have a flat section of ceiling meeting the slope. You could ask for the height of the wall plate to be increased before the roof goes on, this would reduce the size of flat section needed and may eliminate it when the wall slab is on. Also if batons are to be put on the walls this will also leviate against a flat section.

Saruman

As I understand it, these insulated boards have a built in vapour barrier so it shouldn't be a problem.
I'll try screwing them to the roof then. I'll have a friend to help me fit them.
I see the some people say do the roof first and others say do the walls first. What do you think?

arse..biscuits

For the ceiling, you can screw them but you need large washers. There is a type of washer especially for this, they are the same as the top of mushroom fixings.

I'd also use a few mushroom fixings on the wall boards.

I always do the ceiling first, it's not really that important, it just makes the job a bit easier.

Saruman

Great thanks.
Here's some more pics by the way.
http://opa.cig2.canon-europe.com/s/m/G8Biu3ZFS7X

arse..biscuits

Is it a concrete floor? I have a gym in my shed and the floor takes some abuse. If it wasn't concrete I'd have to take it a bit easier on it.

Is there a membrane under the roof? Steel roofs can have a bit of condensation.

It's a fairly handy job if you're any way good with your hands.

fear corcaigh

start at the top and work your way to the bottom.

Saruman

arse..biscuits wrote: »

Is it a concrete floor? I have a gym in my shed and the floor takes some abuse. If it wasn't concrete I'd have to take it a bit easier on it.

Is there a membrane under the roof? Steel roofs can have a bit of condensation.

It's a fairly handy job if you're any way good with your hands.

It's a concrete floor yes. I was planning on putting something down over that like laminate over an insulated membrane and then using mats where there are free weights. Most of the gym will be a treadmill, bike, some sort of stepper, maybe a cross trainer and then one of those multi gyms so the floor itself will not take much abuse.

The roof has a membrane yes so it should be grand.

My platinum board arrives tomorrow so I will try and get started next week. I don't have a free weekend until the end of September though.

arse..biscuits

Saruman wrote: »

It's a concrete floor yes. I was planning on putting something down over that like laminate over an insulated membrane and then using mats where there are free weights. Most of the gym will be a treadmill, bike, some sort of stepper, maybe a cross trainer and then one of those multi gyms so the floor itself will not take much abuse.

The roof has a membrane yes so it should be grand.

My platinum board arrives tomorrow so I will try and get started next week. I don't have a free weekend until the end of September though.

Everything sounds good except your choice of gym equipment

Saruman

arse..biscuits wrote: »

Everything sounds good except your choice of gym equipment

At least if I spend thousands on a gym, I will bloody well use it. Unlike a cheaper gym membership.
Besides, it's a gym/brewery.

arse..biscuits

Saruman wrote: »

At least if I spend thousands on a gym, I will bloody well use it. Unlike a cheaper gym membership.
Besides, it's a gym/brewery.

I love the combination of gym/brewery. I used to brew a bit too but as my shed isn't insulated it is too cold most of the year.

doctorchopper

I have a concrete block shed, I put kingspan in the roof rafters and didn't bother with insulating the walls, you would be surprised as to how warm it gets with just a small electric heater

Saruman

doctorchopper wrote: »

I have a concrete block shed, I put kingspan in the roof rafters and didn't bother with insulating the walls, you would be surprised as to how warm it gets with just a small electric heater

It's more than just to keep it warm. It's also to try and keep it cool in summer. the other reason is that it's harder for spiders etc to make a home in a drywalled room than in a shed. Wife is terrified of them.

arse..biscuits

Saruman wrote: »

It's more than just to keep it warm. It's also to try and keep it cool in summer. the other reason is that it's harder for spiders etc to make a home in a drywalled room than in a shed. Wife is terrified of them.

Generally with a shed/gym/brewery/mancave, the idea is to keep the wife out, fill the place with spiders.

Red Hare

I've just got one of these prefabricated concrete sheds built. its getting insulated at the moment. I'm just interested to see how you got on.. any feedback would be welcome

Saruman

Grand yes. It's nice and insulated and seems to do the job nicely so far. I suppose I will know better in the winter but before it was finished last winter, it was keeping the temp inside a good 6 or 7 degrees warmer than outside without any heating on. With a low powered panel heater on, it jumped up to a comfortable 18c.

Red Hare

Thanks Saruman - thats good to know:)

68 lost souls

Dragging up an old thread as getting a similar shed installed this week. Will be used some of the time as a work shed for odd bit of hobbies and also to store tools and bikes so dampness and moisture is a concern of mine. Have pvc doors and windows speced

So plan at the moment is as follows;

Concrete panels are 500mm wide with a wood baton between them this will allow me to a 2x1 or 2x2 stud to the batons https://brooksonline.ie/catalog/product/view/id/612/s/44x50mm-whitewood-rough-treated-fsc2-2x2/category/37/

Between that put 50mm Rockwoll for insulation.

Then a layer of polythene like this 9r should that go between the concrete panels and the stud before the rockwoll?

https://brooksonline.ie/brooks-1000g-polythene-36m-x-15m

Then 18mm osb
https://brooksonline.ie/timber/osb/osb/smart-ply-18mm-osb-3-2440mmx1220mm-8-x4-ce2-fsc2

I plan on getting electrics and alarm fitted. Was Planning on drilling through the studs and wiring 2.5mm twin and earth between the rockwoll and osb for sockets and ending where a fuse board will be put and then also 1.5mm to a switch position and a where a light fitting will be.

The concrete slab is already poured and set.

I hope to get aws pulled from the existing fuse board out tot the shed.

Does my plan sound correct?

Calahonda52

68 lost souls wrote: »

Concrete panels are 500mm wide with a. Wood baton between them. Out a 2x1 or 2x2 to the batons

Don't follow this: any pictures?

If it were my gaff I would insulate/airtight the roof really well, making sure it is ventilated above the insulation like in a house and have wiring/lights in a service cavity inside the a/t layer.

I wouldn't do the walls as described on the inside as I think you will get lots of condensation on the inside of the concrete panels because the insulation may bring bring the dew point in to the inside face of the concrete panels.

68 lost souls

Sorry realised that my post was littered with errors there. It is something like this on the inside so I can secure studs to the wood between the concrete


Will be able to put pictures of my own tomorrow.

So you would not recommend insulating at all on the walls? What about a damp proof layer? Should I line with polythene sheet or the type of foil bubble wrap and then secure the sheets of osb directly to the wood Barton’s picture in the link above?

Then do I surface mount the electrics down to the sockets and switches etc

Lumen

I think the design depends on to what extent you plan to heat it.

In my unqualified opinion, for an unoccupied wired shed the best approach is to get it as airtight as possible, have no ventilation, and then use a desiccant dehumidifier draining to the outside. On the occasions when you are going to be in it, just open the windows/doors ("purge ventilation"). That sort of dehumidifier creates a small heating effect, which is good. This will only work if you are able to create an almost perfectly sealed environment, and the door in particular may be tricky.

This is a completely different approach to what you'd use for a habitable building, but I reckon has the potential to be much more efficient with much lower humidity. It's closest in concept to the "car bubbles" which are used for storing classic cars and motorbikes.

This goes directly against the usual advice of ventilating a storage shed, but that advice makes no sense to me. Humans need fresh air, inanimate objects don't.

The usual rules about airtightness layers (put them on the inside/warm side of the insulation, make them continuous) still apply.

Calahonda52

What is the roof finish
are you going to use the space above?
Whats the outside finish, especially re the timber?

68 lost souls

Outside finish is pebbles preset into the concrete. It’s a pent style roof, slopes from front to back. The mdf section you can see in the picture is pvc fronted. Roof itself is corrugated insulin’s tiif with vapour barrier

Door is also 5 point locking pvc.

I was hoping to use the roof section for some storage but sure myself yet exactly how it will be. Was hoping to put ladder or folding chairs up there out of the way.

Plan was not too use too much heating except when needed

Calahonda52

A lot of different ideas here re ventilation/humidity control: one option would be spray on a thin layer of foam insulation, IMO any stuff like rock wool etc will be very difficult to get right. The bubble foil you mentioned is complete crap for this job

68 lost souls

Thanks. Now it’s installed I have a better idea of things. The roof won’t be used for storage.

I think maybe as was suggested by someone the roof should be insulated and I am thinking for now at least I won’t insulate the walls. Can do that again in the future if needed.

I will put up polythene and then maybe even just 2x1 batons and 18mm osb, ply or panelling

Sarah 1111

Hi,not sure if its right to add to this thread or start anew - we are converting an old cow shed into a useable space for work and storing furniture, books, etc. We have an insulated concrete slab - concrete block walls which have been newly and properly rendered so watertight, the tin roof will have spray insulation. Inside we will build a stud wall which will have eco earthwool insulation and then plasterboard.
Moisture can't get in from the outside - it has windows and doors (single glazed) and we will be in and out often enough for ventilation. It is important that it doesn't have any condensation, otherwise being very warm isn't that important, just comfortable enough...

Question is: should we put a breathable membrane on the walls between the outside block walls and the stud/insulation? Or is this unnecessary?

Lumen

Vapour control layer should be on the warm side of the insulation, not cold side.

Calahonda52

RH will determine whether you have condensation or not, especially if there is a lot of in and out so you will have to maintain a certain minimum temperature.
http://www.dpcalc.org
you may need to consider a dehumidifier

Stoner

Would you consider external insulation on the shed? You'd keep the height.

Sarah 1111

Calahonda52 wrote: »

RH will determine whether you have condensation or not, especially if there is a lot of in and out so you will have to maintain a certain minimum temperature.
http://www.dpcalc.org
you may need to consider a dehumidifier

yes, I agree, we think we will definitely have a dehumidifier in there.

Sarah 1111

Stoner wrote: »

Would you consider external insulation on the shed? You'd keep the height.

We have already replastered (rendered) the outside - one back wall is hard to get at but we are planning to line that with tin sheets - the place will be watertight - just getting conflicting advice on whether we need a breathable membrane (basically roofing felt) as well... I am not sure how these things work but if its breathable - i.e. allowing any moisture to get out through it - and the concrete block wall behind has been sealed by being rendered - then what's the point?
Would a dehumidifer and ventilation be better?
Proper external insulation is unfortunately beyond the budget I think.

Calahonda52

roofing felt, as generally understood, is not breathable.

You need to distinguish between moisture vapour and moisture: they are not the same.
.
Breathable relates to the vapour passing through it.
Render is not water tight in an absolute sense
You could consider a small MHVR unit which would allow you run the temp high enough to reduce the risk of condensation, or fit a cooling coil to the intake.
It really depends on the economic value of the stuff being stored.
If there is a lot of in and out then maybe a small draught lobby inside the entry door would make sense

Lumen

Calahonda52 wrote: »

You could consider a small MHVR unit which would allow you run the temp high enough to reduce the risk of condensation, or fit a cooling coil to the intake.

That's an interesting idea.

I wonder what the efficiency/effectiveness of MHVR vs dessicant dehumidifier (with no ventilation) is?

I guess it depends on the air tightness. With poor airtightness you're going to be dehumidifying the world.

Calahonda52

Lumen wrote: »

That's an interesting idea.

I wonder what the efficiency/effectiveness of MHVR vs dessicant dehumidifier (with no ventilation) is?

I guess it depends on the air tightness. With poor airtightness you're going to be dehumidifying the world.

vent axis had a small one which I used for two bathrooms in a previous house: it just came on when the showers were in use, I had a 15 minute boost button on it for more odourful tasks:D

MalDoc

Hi,

Sorry to resurrect an old thread.

Also looking to insulate a concrete panel shed.

Will be used mainly as a gym but potentially as an office also down the line.

@68 lost souls it sounds like I've very similar to yourself.

Concrete slabs with a pebble dash on the exterior but a pent style roof instead of an apex.

What I'm thinking is to put up 2" x 1" battens also and then PIR between and also on the roof.

Sheets of ply screwed on to this after.

Reading conflicting advice about a membrane/vapour barrier.

PIR board has foil on both sides and I plan to tape over each joint with aluminium foil also which apparently negates the need for any vapour barrier.....

Sealed the floor already with PVC and will be putting down decent rubber mats.

Don't intend to insulate as even in the recent cold spell it was never that cold to the touch.

What did you decide to after and is there anything you would have done differently now time has passed?

Thanks

10-10-20

If you're going to use it as a gym/office, then you need to think about ventilation in some way - especially if you have foil-backed insulation on the walls all fully taped-up. Questionable in my mind whether you need a VCL there at all, but where would all that moisture end up if it did escape? If it's just going to be sandwiched between the insulation and concrete panels then you'll end up with damp external walls and probable issues with cold spots and maybe mold.

In regard to sealing the floor - do you mean PVA instead of PVC? PVA is a water soluble glue and isn't a sealer. Don't consider it sealed if it's just coated in PVA.

68 lost souls

https://www.boards.ie/discussion/comment/120058964#Comment_120058964

Hey,

I did 50mm thermal board on 3 walls - https://www.goodwins.ie/products/xtratherm-insulated-plasterboard-50mm-8x4-ft.html

On the 4th wall I did 2x2 battens and insulated in between and then plasterboard over so I have wood battens to secure a shelving rack system to.

The roof I put insulation between the rafters and plasterboard over.

The floor I sealed with Chlorinated rubber paint and have some rubber mats on.

Since Covid hit I have ended up working in here most days which had been unexpected and I have a little heater and a dehumidifier in here which is setup to turn on if the humidity gets too high or it gets below 5 degrees.

I think if I had insulated the slab in the first place it would have been a wiser choice given how much time I spend in here now but too late to go back on that. Even just the rubber floor makes a big difference. I didnt worry too much about vapour barriers because I was concerned of in the end trapping moisture and creating mould as s result. It doesnt take long at all to heat up and even if I dont have the heater or dehumudifier on it doesnt get too cold really compared to outside.

Ply would have maybe given me more poitns to anchor too but for my use the plasterboard is fine and looks brighter when I am working in here, was also cheaper. I didn't bother skimming it just taped and skimmed the joints. I siliconed around the bottom where the floor meets the plasterboard.

Ive been tempted to put some of that foil sheet down on the floor under the rubber to see if it makes it even better but the rubber floor tiles did make a big difference cs before I had them down.

MalDoc

https://www.boards.ie/discussion/comment/120059368#Comment_120059368

Hi, sorry I meant PVA. Used a 4:1 water to PVA mix. Sealed might be the wrong word. It was just to keep the dust down more than anything.

Considering I'll be putting rubber tiles on top, do you think there is a need to apply something else also?

I'll be leaving 50-60mm between the roof and back of the insulation boards. The roof itself does have a vapour barrier.

The concrete panels have a cavity on the inside of the shed so would imagine there would be a good bit of airflow even with insulation covering.

It wouldn't be airtight as is either.

Should I be looking to add a vent through the insulation too?

Thanks

MalDoc

https://www.boards.ie/discussion/comment/120059415#Comment_120059415

Thanks for getting back to me so quickly.

I had considered plasterboard alright but thought it might be that bit more difficult to work with.

How did you secure that to the walls without battens?

Would definitely look a lot better than plywood if it's to be used as an office.

Might do plasterboard at either end and ply down the sides.

The pent roof is going to make things awkward so will probably just use 12mm ply there after insulating.

After I started reading up on it I was kicking myself for not considering insulating the slab too but if you got through the last few weeks it sounds more than adequate.

10-10-20

https://www.boards.ie/discussion/comment/120060115#Comment_120060115

Is there a damp proof membrane in the slab at all? With mine I poured a screed over visqueen so that there was no damp coming off the slab directly into the flooring. If you don't have a DPM in the slab then you might need to address that somehow.

MalDoc

https://www.boards.ie/discussion/comment/120060382#Comment_120060382

There is a damp proof membrane in the slab. It's down around 2 months now and dry.

There was a good bit of dust coming off it even when cleaning before I applied the PVA.

10-10-20

ok, good. I'd consider a small vent as it sounds like it could be relatively air-tight (as you can make it with foil insulation and tape. Close it off when you're heating it and open it outside of heating times.

68 lost souls

https://www.boards.ie/discussion/comment/120060219#Comment_120060219

I had an sds drill and used it to drill holes through the plasterboard and into the concrete and used mushroom fittings that hammered in. I believe I also used an expanding adhesive too.

i actually put one batton along the wall with a window that was used also to secure a worktop top.

Here is the before and after

MalDoc

Thanks, looks a decent job!