Hi,
I have a single brick walled garage. I would like to try to insulate it by lining the walls and the ceiling. So I need to line the walls with something like Kingspan. Is there a recommended thickness I should be using or do you just use the thickest you can afford?
I have heard about people mounting these onto battens. Why can't I screw directly into the wall?
Thanks.
I've done precisely this.
I made a stud frame arranged to be just inside the brick wall with a
20mm gap behind for air circulation. The tops were attached to the ceiling joists, and the bottom frame bolted to the floor with DPC material between wood and concrete. The floor probably has DPC but I was not 100% certain. The timber was purchased as sawn and was treated with a proper solvent based preservative (not mamby pamby water based stuff). Pressure treated could have been used.50mm Celotex was fitted into the frames and then taped with foil tape. 18mm ply was screwed to the surface. It has the advantage that one can attach most fitments anywhere,. I have a dust extractor weighing around 100kg. That has aditional fixings to the studs.
For the sloping roof, I used 50mm Celotex again but over the rafters rather than between, again to allow ventilation. For this, I used long screws with large washers to fit it, again taping the joints. At the eaves, I fitted a vent in the soffit boards between each pair of rafters.
I boarded the floor area to create a storage space in the loft. I didn't insulate that. The idea was to allow a gradual rising of heat into the storage space.
Finally I fitted Celotex to the inside of the doors - it's light enough not to make a difference to door operators - and very importantly fitted vinyl seals to cut draughts. Subsequently, the door has been replaced with a thicker one having insulation inside and proper seals on the frames.
The result has been that it now takes around 2kW to heat the place to
18 degrees in the coldest weather. Previously, 12kW of fan heater would have been required to achieve a similar result.One could go for the 80mm Celotex which would take the garage to something close to house standards. I decided that it wasn't worth it.
you can do either.
NT
However screws through kingspan are a cold bridge, and its not that physically robust.
It's a garage. Compared with a single brick wall, the cold bridge through some screws will have minimal effect.
aha- you're saying that if we stick kingspan to a wall then cover it with board, and screw right through it into the wall: then heat will travel along the metal of the screws and heat up the wall or the air gap.
Will this be a significant loss compared with that of wooden battens betweeen kingspan sheets?
[g]
No it won't but this is not a good solution mechanically if you want to fix anything to the wall and doesn't permit ventilation which is also bad
Its kingspan. Compared with a sheet of kingpsan, a cold bridge through some screws will have a noticeable effect.
What part of 'the purpose of insulation is to insulate cold walls from warm rooms' do you not understand?
Yes, although not large..actually why not simply 'no more nails;' the bloody lot together: studding is as much about having something to hang kitchen cupboards on as simply supprting plasterboard.
Have you stopped taking the medication again?
I understand it perfectly well. I also understand context.
Obviously compared with Kingspan and no screws going through having
*some* screws going through will make a difference to that.However if you compare the difference, in the context of a garage with a single brick wall of having:
a) No insulation
b) Kingspan fitted not using screws
c) Kingspan fitted using screws
then the difference between (a) and either (b) or (c) will be vastly more than the difference between (b) and (c).
Moreover, in the context of being able to measure in the garage itself, I would very seriously doubt whether there would be a difference between (b) and (c) that someone installing this as a DIY project could actually measure. If the garage could be encapsulated in a constant temperature source and precision lab instruments used to make measurements, one might just be able to measure the difference.
It isn't a good mechanical solution. With wooden framing and ply covering that, one can fix easily to the ply or to the studs where loads dictate. Otherwise one has to fix through the foam and into the wall behind each time.
Therefore it depends on the application. The OP didn't say whether the space was to be used as a habitable area or as a workshop. If it's the latter, then it would be reasonable to expect that shelves, cupboards etc. would be fitted.
Try doing the calcs. it is surprising how little cold bridging you need to compromise a very highly isnulated surface.
That could be an interesting project. Screws will be a good conductor but the area is minuscule in comparison with the overall wall area. Moreover, they won't gain much heat other than through the heads since there is insulating material all around the sides.
If one had studs fairly close together then the area begins to become significant. IIRC, the U value for a 45mm wooden door is approx 3 W/m^2.K so a stud of 75mm will be at around 2. This is approx
8x worse than Celotex in this application. If the studs are on 600mm centres and 50mm is presented as the face, the proportion of surface area is still only 8% and the studs plus ply on top are still about 2- 3x better than the wall alone, even with no insulation. Once the U value of the Celotex is factored in, it completely dominates the rest anyway. In effect, 92% is insulated like this and the remaining 8% is still a great improvement on the brick so we are very much into 2nd order influences with studs, and with screws down in the noise.
Sorry for the late reply.
I was a bit surprised that a screw through the king span into the wall would let so much heat in/out along the screw. Whilst I understand that metal is a conductor, screws are so tiny I would not have thought they would "leak" a significant amount of heat. Wouldn't a plastic wall plug insulate them? Besides, the loss through a dozen screws must be less than the heat I'm losing now!
I am a bit unsure about the wooden framing. At first I though you put the frame against the wall and attached the king span to that. Now I'm thinking that you make a frame and wedge the kingspan between it, rather than on top. Am I right second time? If so, surely there are heat losses through the wood. Isn't there an advantage to the other method of screwing panels to the wall that all the wall is covered in insulation? Or is wood a good insulator itself?
I see that the advantage of the frame is that shelves can be fixed to it. That's a good idea. Why do you suggest plywood rather than plasterboard? Ply would cost a fortune! OTOH I suppose plasterboard might be easily knocked or damaged in a garage.
One last question: what thickness of kingspan do you recommend. Do you get the thickest you can afford or is there an optimum value?
Thanks.
Plasterboard outside doesn't last long if it's not plastered - it soaks moisture out of the air and becomes very brittle, then when it dries, it crumbles away.
As I understand it, you are correct this time. I beleive you should also have an air gap behind for ventilation which means the framing is not touching the wall.
Or, is the gap just between the framing, behind the insulation?
The idea is that hooks, shelves, etc., can be fixed directly to the
18mm ply, for maximum utility. You only need to screw through into the framing for fixing heavier loads. If you only intend fixing to the framing then you could use thinner sheet material.MBQ
I agree. For this application, I don't think that it's a significant issue.
This was what I did. The frame was mad in sections and then bolted to the ceiling joists and to the floor, using a piece of DPC below the frame. The timber was pressure treated. I left a gap of about 20mm beind the frame and then located the Celotex in the frame sections - i.e. there is an air gap behind the whole lot.
If you calculate the area of timber frame as a proportion of the total wall area, it is quite small. The timber has a heat loss approximately a half of the brick behind it. For the areas of Celotex, the insulation is so good that it dominates anything else.
That was my point. I can fix up to quite medium weight things to ply without worrying about finding studs, having plasterboard crush or being subject to dings. One could use plasterboard on frames instead of ply and then the ability to fix to studs is there either way.
I was able to reduce cost by making a complete project shopping list, including timber, ply and insulation and giving it to several suppliers to quote.
I used 50mm. It was a trade off between improvement to heat loss, loss of space and cost. If you do the calculations, if the walls and roof are insulated with 50mm of Celotex, the next dominant factor is the doors. A large difference can then be made by insulating the doors and fitting weather strips to limit draughts After that, heatloss through the floor becomes significant. Assuming that one is not going to dig up the floor and put in styrofoam and relay the concrete, the only other alternative is to put in a raised (e.g. wooden) floor with insulation in that. In a double garage, it will make a difference of 3-400W compared with doing nothing.
All of this assumes that you are talking about making a workshop or leisure space like a games room. If it's habitable space, then it's a different discussion..
That's exactly it. One could use 12mm ply and fasten to it using spring toggles and similar fixings that would normally be used in plasterboard. I looked at that but decided it wasn't worth it.
18mm ply in construction grade (i.e. imperfect surfaces filled) is not that expensive.HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.