Garage opening detail

[flanagaj]

Can someone cast there eye over the image below and tell me whether this is the correct way for building the garage reveal.  I want the garage door to sit behind the opening, but unsure how the internal block leaf will tie into the returning brick course and whether the cold bridging will be problematic.  My plan was to then use a granite setts between the two reveals and up to the garage slab / DPM upstand.

[Mr Blobby]

Assuming the black line is the garage door inside the reveal (as sectional doors are typically installed) then the inner leaf adjacent to the door should be thermally broken with a strip of PIR.

This is because the reveal is on the cold side.

[flanagaj]

26 minutes ago, Mr Blobby said:

Assuming the black line is the garage door inside the reveal (as sectional doors are typically installed) then the inner leaf adjacent to the door should be thermally broken with a strip of PIR.

This is because the reveal is on the cold side.

But how do you thermally break with PIR.  Do you have a drawing or an image that shows this?

[Nickfromwales]

Is this attached or detached? Fire regs may need that closed and FR.

 

Closing as per the pic is normal, and garages are classed as cold ventilated spaces so why would you care about a small cold bridge when the whole garage is 'cold'?

[flanagaj]

6 minutes ago, Nickfromwales said:

Is this attached or detached? Fire regs may need that closed and FR.

 

Closing as per the pic is normal, and garages are classed as cold ventilated spaces so why would you care about a small cold bridge when the whole garage is 'cold'?

Garage is attached.  You are most likely correct that the cold bridging will be negligible and I can close off as per the diagram.

[Nickfromwales]

3 minutes ago, flanagaj said:

Garage is attached.  You are most likely correct that the cold bridging will be negligible and I can close off as per the diagram.

Indeed! Just be sure to properly close any cavities, above the garage door / pedestrian doors & windows to make this properly FR. BCO's sometimes forget this, and one previous instance saw a head of doorway almost closed with only a 5mm strip of uPVC across the cavity; I chirped up and he quickly "added that to his list"...............as that needed to be closed with mechanically fixed FR PB, with all joints sealed with intumescent caulk.

[flanagaj]

27 minutes ago, Nickfromwales said:

Indeed! Just be sure to properly close any cavities, above the garage door / pedestrian doors & windows to make this properly FR. BCO's sometimes forget this, and one previous instance saw a head of doorway almost closed with only a 5mm strip of uPVC across the cavity; I chirped up and he quickly "added that to his list"...............as that needed to be closed with mechanically fixed FR PB, with all joints sealed with intumescent caulk.

One other question.  Do I finish the slab at the back of the inner leaf blockwork or should the slab come through the opening and finish level with the exterior leaf.  If I do the later, do the bricks that close the cavity just sit on top of the lean cavity fill (left image) or should they sit on the concrete slab (right image)  

Eg, if you were looking at eye level from the front would it be the left or the right image below

Edited yesterday at 11:01 by flanagaj
Added image

[Mr Blobby]

2 hours ago, flanagaj said:

But how do you thermally break with PIR.  Do you have a drawing or an image that shows this?

 

Like this...

 

 

This is how ours is built.  The bricklayers put a strip of PIR about 40mm wide into the blockwork.  If I get down the site later I'll get a photo.

 

Edited yesterday at 12:30 by Mr Blobby

[Nickfromwales]

5 hours ago, flanagaj said:

One other question.  Do I finish the slab at the back of the inner leaf blockwork or should the slab come through the opening and finish level with the exterior leaf.  If I do the later, do the bricks that close the cavity just sit on top of the lean cavity fill (left image) or should they sit on the concrete slab (right image)  

Eg, if you were looking at eye level from the front would it be the left or the right image below

Wouldn't the bricks start at slab / TOC  (top of concrete) with the DPC? Looks too emphasised there (imo). 

[saveasteading]

I like to stop a slab short of the inner leaf, then the ramp down is from there and the door bottom seal sits on a slope and water doesn't get through.

This is because bottom seals dont really seal, but water gives up climbing the slope after about 50mm.

 

To form this edge the shutter is simply placed against the inner leaf with any extra packing needed. This assume you now where the bottom of the door will be.

[flanagaj]

15 hours ago, saveasteading said:

I like to stop a slab short of the inner leaf, then the ramp down is from there and the door bottom seal sits on a slope and water doesn't get through.

This is because bottom seals dont really seal, but water gives up climbing the slope after about 50mm.

 

To form this edge the shutter is simply placed against the inner leaf with any extra packing needed. This assume you now where the bottom of the door will be.

Thanks @saveasteading that was my exact thought process as well.  I can then lap up the DPM on the inside of the inner leaf which can then potentially be placed under the bottom seal rail of the garage door.  This will stop damp from being able to make it's way through into the garage.  I always that that whilst taking the slab and mesh through the opening gives a solid base for vehicles going into the garage, the top will be exposed to the elements and if you have a garage door that sits behind the inner leaf, you have a visible 350mm slab of concrete that if not finished well when poured will look a bit naff.

[saveasteading]

36 minutes ago, flanagaj said:

concrete that if not finished well when poured will look a bit naff

It's a ramp. So either tamp then float smooth, or deliberately tamp with grooves down the slope. The latter looks rugged and is slip resistant, but gathers muck.

But the former only looks imperfect when you are on your knees doing it, and nobody else will look.