Garage ceiling insulation & garage door

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18 Jul 2016
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I have a classic double car garage (flat roof and joist) and I would like to insulate the ceiling to keep it a bit more comfortable during winter. I am planning to use some multifoil, stapled directly to the joists, then add some plasterboard to have a cleaner look.

The main issue I have is the garage door. I have an automatic garage door with rails on each side plus a central rail in which runs the chain that pulls the garage door open. I can easily adjust the supporting brackets for each of the side rail to account for the foil & plasterboard thickness without changing the height of the rails. However, I have no way to adjust the central rail, as this one is directly fixed to the joist

Lowering the central rail would mean that it would not be at the same height as the side rails (which I believe would be an issue), and lowering all three rails to keep them all at the same height seems impossible due to the bending of the rails.

Another option would be to plasterboard around the central rail. Not the best/cleanest job, but probably the easiest.

I was hoping someone had a similar situation and could share some ideas/tips/knowledge.

Some photos below to clarify.
Thanks !

Side rail with L bracket that can be adjusted (foil and plasterboard would go between the joist and the bracket)

Side rail on the other side

Central rail, directly attached to the joist. Fitting foil and plasterboard between this rail and the joist would get this rail out of alignment with the side rails

Another view of the central rail

Curve of the side rail. Lowering the side rails would require to refit completely the door (too big of a job for me)


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I do not believe you can drop all three rails as the door mechanism and tracks will not allow it. I think you are going to have to go with your original thoughts, boxing in over the top of the central rail. The door looks like a Hormann, and at the £2.5K price it is not something you want to replace. The 45mm insulation in it does a good job as well.

Insulate above, and plasterboard to it, that way you still have a working door. Although not the prettiest, it is a workshop and not a living room, you'll probably get used to it, and be glad you didn't do a load of work to move the door
Does that centre rail just carry the drag chain.
Is there a ny clearance between top of door and rail, when door is in the open position?
The house into which we recently moved had similar garage doors - albeit probably 20+ years old (not 3). One centre rail and motor needed to be relocated as it impeded plans to use part of the garage space for a utility room.

We ended up replacing both garage doors with roller shutters which got rid of all the tracks and motors which disrupted the internal space. Roller doors also run in tracks which are likely to be more draught resistant than the original up and over steel doors.
I had a Hormann door at our last house. It is a wonderful thing, about 50mm thick with inner and outer surfaces of steel and heavily insulated between. The track system also has draught seals. It has good noise and sound insulation properties.
Our present bungalow has two roller doors. They look nice, but with about a 12mm thick folded aluminium sandwich construction they lack the build quality of the Hormann and let draughts in around the vertical runner tracks.

Does that centre rail just carry the drag chain.
Is there a ny clearance between top of door and rail, when door is in the open position?
Yes, the centre rail just carries the drag chain. There is a bit of clearance when the door is open between the rail and the door.
My concern about lowering the centre rail is that it would not be at the same level as the side rails.
The centre rail is not a guide rail then. So I don't see that lowering it a small amount would affect it.
You could do a simple test run by simply loosening the rail and adding a packer along g its length equal to the gap you need, then try the door opening mechanism to see if it's OK.
I put rockwool insulation i between joists /vapour barrier and boarded ceiling with plastic interlocking facia boards 5mtrm300mm lot easier to handle and better at reflecting light one man job good at keeping noise down as we’ll fitted led lights at same time then boarded walls in ply .i heat it with Chinese heater it great. Like toast in there now
Quick note, I think that multifoil needs an air gap on both sides to be effective, worth checking first.

Personally I'd skip that and just put mineral wool between the joists, or celotex/Kingspan, then board over.
Lowering the central rail/chain guide by the thickness of plasterboard will not affect the operation of the door. There simply needs to be clearance between the door and this rail - nothing else, as the articulated action of the arm compensates. There is nothing precise about the level of the chain guide.
Within reason, be careful to reset the side rails at the original height and you won't have any problems. If you significantly alter the height of the centre rail the only potential issue would be the motor & chain allowing the door to hit the ground before it reaches the end of its travel, resulting in the door rising again. Easily reset on the panel at the back of the lifter - Google if you don't have the manual.
Yes, you're right , something like 25 mm between foil and plasterboard.
Insulation boards would be much more expensive.
You could fit some 2x1 batons on the insides of the joists set back, about 30mm, then cut foil to width and staple the foil to them. This would give the 25mm air gap.