Garage door insulation

[Alun12]

Hi, 

 

I hope someone can help.  I'm planning to use my garage as a workshop all year round and want to get an insulated garage door.  I understand that there are 'R' and 'U' ratings associated with insulated garage doors and so asked one supplier what their doors are rated as. They sent me this explanation  - "acknowledges the magnitudes of heat penetration rate U to the extent from 4,8 to 5,4 [W/m2k]".

 

Can someone tell me what the 'U' or 'R' rating is for this? Would the insulation in the door be good enough at keeping the cold out?

 

I found a useful table here https://www.doorsdoneright.net/r/ that lists R values, so I think I'd be looking at an R-8 and above.

 

 

Many thanks,

Alun

[Nick Thomas]

I was staring at my garage door last night while planing some wood. What a good idea ^^.

 

It sounds like your supplier is saying their doors have a U value from 4.8 to 5.4 W/m²K, which is... not much. Basically the same as single glazing. You can convert it to an R value by dividing 1 by it: U=5.4 = R=0.18. Doesn't sound insulated at all...

 

("Rating" is a weird term to use here, but they're giving you the unit so I'm confident it's not an obscure rating scheme. Language barrier?)

 

Don't think I'd get planning permission to convert my garage into living space, so if well-insulated garage doors *do* exist that might help a lot.

[RobLe]

I’ve been converting our flat roof garage into a workshop.  It’s adjoined to the house, and has an up-and-over metal door.  Ages ago I put 50mm of celotex on the inside of the metal door, giving it a calculated U value of around 0.5W/m2k - of course this ignores draughts around it.  

Calc:  celotex lambda=0.025W/mk, so U=0.025W/mk  /  0.05m=0.5W/m2k
The outside wall has 100mm celotex, floor 50mm, roof 150mm equivalent.

The insulation is mostly internal - likely I’ll only heat it locally when needed with IR panels rather than with a thermostat.

For comparison with the U values you gave; an old single glazed window U value is 6W/m2k, modern double glaze is 1.2W/m2k.  I think you’ll be disappointed with a 5W/m2k ‘insulated’ door.

 

[elite]

When I looked at this a couple of years ago, the Hormann sectional doors LPU42 and LPU67 looked the best, or at least were one of the few that provided what looked like sensible specification which came to a 1.4 W/m2k

 

 

[Russell griffiths]

I’ve been looking at this recently 

it looked like the cheaper end had 25mm panels and the dear ones 40mm panels. 
look for one with a threshold that has an upstand that the door closes down to with rubber sealing strip. 
 

I thought the u value quoted was pointless as the weakest area would be air leakage around the seals. 

[saveasteading]

Garage doors are for garages, so the insulation and seals are passable for that. For an office  fill the door in with insulated stud and include a window. The remaining surfaces are presumably uninsulated so you will be cold and have damp paperwork, or a huge electric bill.