Raising An Existing Concrete Floor

[Willmott85]

Good Afternoon, hope everyone is well.

I have a question about how best to go about raising the level of an existing concrete floor in my garage.

To give a bit of background, the property had a large side extension added to it ~20 years ago, long before we bought the property. There is a concrete floor in the garage, which is below the level of the main house, by approximately 100mm.

I would like to partition part of the garage to create a utility/walk in larder room, in doing so raising the level to match the adjacent kitchen.

2 external walls are cavity wall, brick outside and block inside.

The external ground level has a reasonable slope on it, and at the point where I would like to create the new room, the exisiting concrete floor level is ~6 bricks up from ground level (see external picture).

I do not know what is beneath the existing concrete floor. I could excavate part of it out, but not sure this is neccesary. Given I have ~100mm to add, I could add in some insulation.

1. What would be the best way to raise the level?
   • Concrete or timber?
2. Can I place insulation on top of the existing concrete floor, before pouring the slab?
3. I assume a vapour barrier is required, does this need to go up the internal block wall, and how far?

The 2 external cavity walls do have insulation in it, but I think I will take the opportunity to insulate the wall internally before plasterboarding. I am thinking of creating a stud timber frame attached to the blocks, with the insulation between it. Nothing too think, 50/60mm.

1. Would you poor the new floor slab, then add the wall insulation butting on top?
2. Or, insulate the wall then pour the slab?

Thanks in advance for any help and advice.

<a href="https://ibb.co/WxzYMJf"><img src="https://i.ibb.co/WxzYMJf/20210307-142249.jpg" alt="20210307-142249" border="0" /></a>

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[23vc]

Are you doing a garage conversion then, sounds like you’re converting garage to habitable space? Be aware that normally involves building regs, for insulation etc. And would come to light if you sold the house etc
Garage floor is currently lower as it’s a fire regulation, to do with fuel spillages from garage not being able to get into the house.
You could screed, insulate and screed, or do a floating ply/osb/chipboard over insulation. Yeah include a dpm if you don’t know if there currently is one.

 

[Willmott85]

Thanks for the reply.

Yes, converting part of it to habitable space. In total the length of the garage is ~ 15 meters. This new space with have a partition to seperate off the garage section, which would remain at the original level.

Building regs is fine.

 

[23vc]

Just speak to BCO then and find out what they want in terms of insulation. Probably involve a fire door into the non-converted part too (if there’s a doorway) and/or fireline plasterboard