Internal garage door- insulated

Hi- we have had our retrofit survey done by CAFS (Cumbria Action for sustainability). We have a garage attached to our semi with 2 bedrooms above it. At ground level we have a door from the utility into the garage which is currently a timber internal door which has the fire strip in it. A google search tells me this door should be FD30 rated. The survey has recommended replacing it with an insulated (PVC) door.
I’ve had a look online and I’m struggling to find an insulated FD30 rated door- any suggestions? The current door has been heavily draught proofed but the utility does get very cold, and I wouldn’t mind a more secure door there anyway.
The survey has also recommended insulating the internal walls of the garage which are effectively our external house walls- has anyone done this and what specification/materials did you use?- keen to do it ourselves if possible.

I doubt that you will find a fire rated PVC door but I do think that somewhere out there it will be possible to find a fire rated wood, aluminium, composite or steal door with mineral insulation. You would probably need to be very wealthy to get a steal one but by its very nature steal is fire resistant. Aluminium, not so much (remember RFA Sir Galahad, 08/06/82).

Our garage is similar and we had condensation forming on the wall to the kitchen. I dry-lined the wall with a timber stud frame and 50mm expanded foam insulation topped by plasterboard and we haven’t has a problem since.

When insulating internally remember that the section of wall between floors is also part of your building envelope. To avoid cold patches above ceiling height, potentially causing condensation to form and run down behind the insulation below, it is good to cut a slice off the ceiling and insert insulation up to the floorboards above. Then depending on the space you have left yourself either dry line the wall up to the ceiling or floor (without fixing above the ceiling, unless you can access it from above). The remaining gap can be plastered over and decorated.

I can share what I have done with our house that has a similar layout as described. Our fire door was fitted into a frame that was not plumb. I used vitaseal 600 that has a flame retardant between the door and frame and it works very well.

The garage side of the wall I insulated with Rockwool rain-screen duo- probably overkill as this wall was never going to get exposed to rain. It is fitted like external wall insulation and covered with breather membrane. This works very well.

Done in December 2021


Very interested, especially in the photo of the the garage wall showing the consumer unit etc. Did you do anything extra to insulate them?

You should never insulate a consumer unit, on the contrary you may want to cool it.

Heat from the consumer unit is wasted energy and upgrading components may reduce that loss. Hot electrics/electronics work inefficiently, so it might be worth arranging a cool(er) airflow over it to bring the temperature nearer to room temperature.

Hi, the consumer unit is exposed and not insulated. The peak temperature in the image is 7.8℃ so there is no overheating. The benefit has been the heat gain and retention. Here are some numbers -