New linked garage floor level above DPC!?

[jeffsmith]

Hi folks,

Got a bit of a dilemma on my hands:

TLDR: Overcoming the issue of bridging the DPC with an extension of this type.

Semi detached property looking to build a new linked garage on the side.

Ground level directly outside house is standard 3 bricks beneath DPC but then slopes away from the house by about 2 feet over the width of the proposed garage.

The house itself is set back from the road by about 2m and is two or so feet lower than road level. I want to build my garage as close as possible to the height of the road to make the drive in front of it as flat as possible and to match the heights of my garden out back and the land to the right of the property.

Here's a quick sketch to explain:

Untitled

• jeffsmith
• 2 Mar 2014
• 1

Untitled

• jeffsmith
• 2 Mar 2014
• 1

My issue is that this will bridge my DPC resulting in moisture ingress to the house.

Are there any simple or commonly used methods to solve this problem?

Thanks for reading,
Jeff

 

[conny]

As I'm not a builder I can only give you my idea of how to possibly do it. No doubt if I'm talking a load of tosh someone will tell me, Lol.

I would suggest inserting a length of DPC to overlap the dpc in the house, (this would obviously mean removing at least half the depth of the mortar joint), and make it wide enough to go up the outer surface of the wall before bending at right angles to insert between the courses of brick forming the garage wall.

If you are only building front, rear and outer side wall for the garage and using the house wall as one side then you simply need to extend the house DPC in said manner to lap into the garage DPC. (If that makes sense).

You will of course have to lay a DPM under the concrete floor of the garage to lap up the side of the house wall to a point above the DPC to avoid bridging it.

 

[jeffsmith]

Hi again,

So I'm now thinking that by meeting the dpc on the new walls with the house wall and by introducing a layer of gravel into a gap between the concrete base and the house wall I should be able prevent or at least minimise moisture ingress.

What do you think?

 

[trowlerman]

does your house have a cavity ?

 

[jeffsmith]

Yes it does - it's 80s construction.

Here's a rough sketch of what I'm planning.

Not entirely sure I've drawn the internal floor correctly but you get the picture!

Untitled

• jeffsmith
• 7 Mar 2014
• 1

Do you think this will work?

Jeffy

 

[themiddleagedun]

As long as there isn't a door joining the house to the garage there's no problem. You don't need the gravel, run the concrete all the way to the walls.

 

[trowlerman]

theres no problem there as you have a cavity, all I would do is lap the polythene up the the side of your house ,tak on the brickwork with some roof batten and then cut of flush with top of concrete once it has set ,job done

 

[jeffsmith]

THANKS FOR ALL THE REPLIES!!!! REALLY HELPFUL!!!!

themiddleagedun No, I'm not planning to fit a door between the garage and the house.

trowlerman Thanks for the advice! Is this standard practice?


So on my drawings should I just show the vapour barrier lining up the inside of the wall?

Also if my DPC is higher in the single skin brick garage than on the house am I OK just to place some DPC vertically in the join?

Thanks for taking the time to help!