How to close reveals for integrated garage

[ruggers]

I need advice of the best way to close off my garage door reveal for finishing plaster.

 

I'm building a house with an integrated garage which sits under a first floor bedroom. The build is partial fill cavity 100 block, 100 pir, 50 air gap, 100 face brick.

 

I'm aware of thermal bridging using the returned block method, and wont be doing this on the rest of the house, but would it be the best option for my garage door reveals to provide a solid backing for rendered reveal, or what other options do i have?

 

Upvc i think will get scuffed over the years in anthracite. Adding plastic cavity closers could be flimsy and would likely require a lot of mesh?

 

Rendered reveals would be sand and cement, or k rend tc15.

[nod]

It is the best option for the garage 

 

[Nickfromwales]

2 hours ago, ruggers said:

I'm aware of thermal bridging using the returned block method, and wont be doing this on the rest of the house, but would it be the best option for my garage door reveals to provide a solid backing for rendered reveal, or what other options do i have?

It’s a different issue to the rest of the house, as your internal leaf is outside the garage door, ergo it’s permanently cold. As the ambient in the garage isn’t the heated ambient of the house, the delta T between the two will be near inconsequential, plus the windows and doors will bridge their respective cavities, so this is apples/oranges.

 

K rend will have the mesh to sit across the vertical dpc, so that would have the least risk of cracking, whereas s&c render will defo hairline crack there. 
 

You can manage that with expanded metal, to bridge the gap. 

[ADLIan]

No need for insulated cavity closer or similar measure as garage is unheated (normally).

[ruggers]

Thanks guys. I just wanted to check while im at the setting out stage for inner leaf dpc course.

 

I understand the princliples of heat loss for the thermal envelope and setting windows back, fully insulating reveals etc, but wanted to make sure the garage was being done the best way to prevent the cracking you refer to. Builder wanted to leave open and upvc over it but i said its a bit ugly. Ive had them hairline cracks on my current garage reveals.

 

So having never used the vertical dpc foam insert, can you tell me how its installed and is it just one thickness of foam bonded to dpc?

 

Is it a compression fit installed when the lintel goes in with the top being bedded in under the lintel?

Edited Saturday at 16:11 by ruggers

[Nickfromwales]

3 hours ago, ruggers said:

Thanks guys. I just wanted to check while im at the setting out stage for inner leaf dpc course.

 

I understand the principles of heat loss for the thermal envelope and setting windows back, fully insulating reveals etc, but wanted to make sure the garage was being done the best way to prevent the cracking you refer to. Builder wanted to leave open and upvc over it but i said its a bit ugly. Ive had them hairline cracks on my current garage reveals.

 

So having never used the vertical dpc foam insert, can you tell me how its installed and is it just one thickness of foam bonded to dpc?

 

Is it a compression fit installed when the lintel goes in with the top being bedded in under the lintel?

I'd just use regular DPC and then mastic it really well, then webbing and K-Rend or expanded metal and S&C render. I'd only use the foam type product if this was being left on show.

[ruggers]

Thanks Nick. I suppose the foams for minor insulation and in this case not required, so just keep the gap to a fingers width, bed the 100mm dpc under the lintel on the inner leaf and then run a bead of adhesive on the wall and stick the dpc to the cavity side of the inner leaf. Then let the mesh bridge the gap & K rend TC 15 over both.

 

Could always add some low expansion gun foam between the dpc and returning block to help support the mesh bridging the gap if needed.

[Nickfromwales]

1 hour ago, ruggers said:

Could always add some low expansion gun foam between the dpc and returning block to help support the mesh bridging the gap if needed.

The mesh doesn’t even need that tbh, and foam will do zilch here for strength afaic.
 

Just use the joint/frame mastic and get it into the gap as best you practically can.

 

DPC return faces should only leave a gap small enough to point these with mortar, clean back, and then top with mastic.
 

The mastic will carry the damp proofing of that joint, from leaf to leaf, allowing the K rend system to fly over without any bridging. 

[ETC]

?

[Nickfromwales]

3 hours ago, ETC said:

?

What he said....

[ETC]

No need to insulate the wall.

DPC shown in optimum location for damp penetration.

[Nickfromwales]

4 hours ago, ETC said:

No need to insulate the wall.

DPC shown in optimum location for damp penetration.

That’ll have to be made fire rated with FR PB if the joint is internal to the garage, as there’s a habitable space above it? 
 

Layer of FR PB over the DPC or intumescent mastic there? 
 

@ruggers, if there’s a specific side/rear doorway out of the garage it’ll need the same FR attention to that opening too. 

[ruggers]

Would my original sketch not be a better set out so the dpc is external to the building.

 

There will be 100mm insulation in the garage walls too and 50mm insulated sectional door on the garage.

 

No side doors to outside, only an internal door to utility room.

[Nickfromwales]

16 minutes ago, ruggers said:

Would my original sketch not be a better set out so the dpc is external to the building.

 

There will be 100mm insulation in the garage walls too and 50mm insulated sectional door on the garage.

 

No side doors to outside, only an internal door to utility room.

Doorway to house will need the opening to be FR. Assuming FR door and lining will be installed here, with the lining bridging the cavity?

 

16 minutes ago, ruggers said:

Would my original sketch not be a better set out so the dpc is external to the building.

I’d do as @ETC had suggested, much better solution. 
 

You’ll be using a frame sealant between the render and the frame of the garage door for your weather seal, so no issue the afaic. 

[ETC]

3 hours ago, Nickfromwales said:

That’ll have to be made fire rated with FR PB if the joint is internal to the garage, as there’s a habitable space above it? 

Why?

[ETC]

Waste of money insulating the garage if it’s not heated. Insulate the wall between the garage and utility and the floor between the garage and any habitable (and heated) accommodation above. No heat = no insulation required.

[Nickfromwales]

8 hours ago, ETC said:

Why?

To stop fire / flames rising up the cavity, should a fire break out in the garage.