Integral garage conversion - dig for foundation or lintel?

[bettyclueless]

Hi,

Looking for some advice on getting my garage conversion done. The house was built around 1989/1990 and is a typical Barratt 'newbuild' type, with garage attached.

I've had several quotes where I've been told they need to dig down to check the depth of the current foundations, and dig footings for a new front wall and window.

Now I've had one guy quote that they'd install the concrete lintels into the existing brickwork below ground level.

Another guy quoted me that he'd not touch the concrete and just build upwards off the ground, laying one layer of brick and then the lintel to support the rest of the wall and window - he said that this was sufficient and would pass building regulation inspection because the age of the house and it being newbuild with attached garage, the foundations be sufficient.

I'm wanting to go with guy 2 but just need to know which method is best? Prices and project time are approx. the same for both quotes.

Many thanks in advance!

 

[noseall]

You would typically do an exploratory dig to find a footing (some have them some don't) and if there is no foundation then put some concrete back in the hole that has been dug.

You can use a lintel but we would only go down this route if the ground conditions meant that you would have to go deep for a standard strip.

 

[bettyclueless]

hi, thanks for the reply.

I'm not sure what you mean by ground conditions for using a lintel - can you please elaborate?

My main concern is the difference between the two quotes - where one guy has mentioned putting a lintel below ground, whereas the other said the lintel would sit onto of a first layer of bricks. Are both these methods sound, and do they both comply with UK building regulator standards?

I've been told (not 100% confirmed) that when the house was built the garage would have had to pass building regulations already because its attached to the main house. Does anyone here know about this standard?

 

[pred]

"If in doubt dig it out"

My talent is wasted on here.

Seriously, I would be reluctant to drill holes because if there is a DPM you're going put a hole through it.

Are you going to use it as an office or living space?

Building regs have moved on since 89/90.

Have you got a 4" step down into the garage now, I think you will no longer require that if you're converting, so I would go down about 16" below finished floor level, then backfill it with 100mm half to dust, whack that down, 10mm and blind, DPM 100mm celotex, 100mm concrete and finish off with a 50mm screed.

You then know it's a proper job.

 

[bettyclueless]

hi,

it'll be a living space.

There is approx 4-6inches difference in height between the garage and the floor of the house, so its been suggested that a waterproof membrane be placed over the existing concrete and then a floating floor with insulation/timber be built.

With the garage being integral, is there such need to dig down 16inches and do all that you described? It seems like way too much work for something that seems...simple?

I'm a building novice so I may be talking nonsense!

 

[pred]

hi,

it'll be a living space.

There is approx 4-6inches difference in height between the garage and the floor of the house, so its been suggested that a waterproof membrane be placed over the existing concrete and then a floating floor with insulation/timber be built.

With the garage being integral, is there such need to dig down 16inches and do all that you described? It seems like way too much work for something that seems...simple?

I'm a building novice so I may be talking nonsense!

I usually go OTT but don't get problems at a later date, 16" down from FINISHED floor level. So if you have 6" now another 10" to go. BUT different builders use different techniques. I like screed finish.

 

[noseall]

If in doubt - get it designed!

Once you have a drawing the builders are all singing from the same song sheet instead of guessing, whilst you have peace of mind.