Damp Garage - Integral Garage Floor below DPC

[Captain Mike]

I live in a conventionally brick built detached house, constructed 8 years ago. It has taken me until now to notice that the concrete floor of integral double garage is one course of bricks below the DPC. This bottom course leeches salt out of the bricks and conducts dampness through to anything touching against it. e.g. cardboard boxes. It also seems to have encouraged the entry of wood lice into the house. Of the 4 walls of the garage, one is to the front with 2 separate up-and-over doors, one at the side is an external wall, the other side wall backs onto the hall and cloakroom, and the rear wall backs onto the kitchen and utility room.

Should the garage floor have been constructed below the DPC in the first place?

How can I now eradicate the dampness in this bottom course of brickwork?

Grateful for any advice
Mike Schofield
(Bristol)

 

[masona]

Should the garage floor have been constructed below the DPC in the first place?

Yes !

How can I now eradicate the dampness in this bottom course of brickwork?

The dampness maybe because of poor ventilation.

 

[Captain Mike]

Thanks Mason A but I think that with all the gaps around the up-and-over doors there should be adequate ventilation.

 

[masona]

I'm afraid not because the air coming in got nowhere to go. If you open the front and back door of your house you have a air-flow or circulation of air. If air coming in, it need to get out, so outside air pressure is greater than inside therefore becoming trapped air.

 

[Captain Mike]

Is that a design problem then. I don't want to live in a house where I have to keep the back door open all the time!!

 

[masona]

I don't think you have anything to worry about, you may have what is called Efflorescence but can't say without seeing it. If the bricks are wet/damp all the time then maybe a leaking pipe somewhere ????

If it only conducts dampness when anything touching against it, then this maybe a condensation trap with poor ventilation.

A surveyor will be able to help you if there is any problem. The only time I be worry if it's wet all the time.

 

[DAZB]

It will greatly improve the problem of inadequate airflow if you install a pair of equally spaced airbricks to the external wall and that will give you a regular flow of fresh air into the garage. If you want to keep out the bugs ( and I'm with you on that score) then you can fit a wall vent with a fine insect mesh on the internal side of the airbrick.

 

[Captain Mike]

Thanks very much everyone. I'll now make sute that boxes etc are not touching anyn of the walls and have bought an electronic gadget to get rid of the bugs - I hope!!