Garage conversion & doorway opening

[Robert Green]

hi all,

I have trawled through the threads to no avail, if I have missed something please forgive me but after days of searching I’m seeking advice.

I am at the start of converting existing garage into a living room. BC have been informed and a structural engineer has done his job.

Firstly,
I am going to be knocking through from the existing living room in the garage creating a 1200 wide opening. The old external wall is 500mm thick stone. The structural engineer has specified 3no r6 concrete lintels at 1500 wide. I’m at a bit of a loss as to where to install the 3rd lintel. Any ideas?

Secondly,
The driveway slopes down as it hits the front of the garage so when the garage door comes out I’ll be building up slightly to allow for new patio doors to be installed. This has led us to concreting the floor to raise the new floor height. The old floor was soil/rubble/slabs, basically not fit for purpose.
Is this new concrete floor ok being installed above the old dpc?
Do I need to be creating a cavity below the patio doors and if so how do I go about bridging this gap once the floor has been raised/concreted.

I must state that the garage is double skin as it is double story with bedrooms above. Cavities are closed at the garage door opening.

Also, bc have asked to inspect once drains have been installed. I’m at a loss with this as there will be no water services in the living room!?

Any advice is welcomed, thanks for your time.

 

[noseall]

Firstly,
I am going to be knocking through from the existing living room in the garage creating a 1200 wide opening. The old external wall is 500mm thick stone. The structural engineer has specified 3no r6 concrete lintels at 1500 wide. I’m at a bit of a loss as to where to install the 3rd lintel. Any ideas?

At 500mm thick, your wall will benefit from x3, 150mm wide lintels laid side by side. Probably.

Secondly,
The driveway slopes down as it hits the front of the garage so when the garage door comes out I’ll be building up slightly to allow for new patio doors to be installed. This has led us to concreting the floor to raise the new floor height. The old floor was soil/rubble/slabs, basically not fit for purpose.
Is this new concrete floor ok being installed above the old dpc?

Yes. Matching into the existing floor level is the important thing. We would remove some of the masonry at skirting level (right through from new to existing), where the new door opening occurs and base all of our FFL's calculations from there.

Do I need to be creating a cavity below the patio doors and if so how do I go about bridging this gap once the floor has been raised/concreted.

No. One would normally concrete or screed right up to the door threshold thus omitting any cavity masonry where there are door openings. We build our extension foundation masonry as cavity wall (openings included) then later on remove the inner (top) course of masonry to allow the screed to go right up to the door threshold. Other builders set out the openings at the foundation stage, particularly those that wish to lay a floated slab rather than a (later) screed.

Also, bc have asked to inspect once drains have been installed. I’m at a loss with this as there will be no water services in the living room!?

Its a generic request. Ignore it. Just like the generic..."have you got concrete arriving on site" when requesting a roof visit. Lol. They will however wish to look at the foundation trench you dig for the front elevation masonry.
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[Robert Green]

Thanks for the response. Very helpful info.