Damp - Victorian brick porch

[andy.brazier]

Our house was built around 1905. It has a porch to the front door with half-height brick walls with windows all around. The walls are very damp. It did have render on the outside to ground level. I have chipped most off (some was very loose) and it seems very hard, so I suspect it is cement based, and so not breathing. I can see no evidence of any attempt to create a DPC. Internally, it looks like someone has used a 'special' paint that may be water proof.

The brick work is in poor condition, so will need to be rendered. Should I inject a DPC before rendering? Or can I just use a lime render without a PDC?

Internally, the porch is unheated. It has quarry tiles, but I do not know what they sit on. Any advice most welcome. My wife is keen for me to get on and re-render, but I have told her the wall will need to dry for several years before I get around to it! AB

[The Natural Philosopher]

If you intend stopping evaporation outwards with a hard render, then you need to damp proof it.

May be easier to remove a btibk at a time and shove a DPC in that way..

Probably wet earth..by teh sound of it.

I'd take the bloody thing down and rebuild it frankly.

[dom]

Where does the moisture appear to be coming from? Rising? Penetrating? Condensation? Are the windows in good condition? Could the damp be due to rain creeping around them? Is there any build up of soil/vegetation around the walls? Is the porch original or perhaps a less well considered add-on to the house?

Assuming the front wall of your house has a slate dampcourse (and rising damp is the dominant cause of the porch problem), I'd consider slotting the brickwork of the porch bit by bit and add one at the same level.

I'm not clear whether you mean an open to the outside porch (i.e. walk through porch to front door) or one that is open the inside of the house (i.e. closed to the weather).

Once thoroughly dry, a lime render sounds appropriate - will allow moisture out, whilst preventing rain being trapped.

[Stuart Noble]

Yes, it's a magical one way process. It allows moisture out, but not in. The moisture that has to get out hasn't previously come in of course.

[andy.brazier]

The porch has a door to outside and a door to the house. It is therefore a box. I guess it does not get much ventilation, so condensation may also be a problem. So I now have two more questions

1. What can I use to form a PDC if I remove bricks as suggested. If I use the black plastic, does it need to be a continuous length or is it OK to cut up and insert a bit at a time?
2. Is there any mileage in adding some insulation to the wall to warm it up and so reduce condensation? If so, how can this be done without creating more damp problems?

Thanks

AB

[dom]

Lime mortar does indeed wick moisture out. But I was refering to the smooth, rain-shedding surface rather than the poor-condition brickwork likely to trap rain, that the OP refered to.

[dom]

Was the porch always a closed box or is one of the doors a later add-on? You really need to find the source(s) of the moisture before attempting cures.

[andy.brazier]

I accept what you say about causes and cures. However, I can see that no DPC means rising damp is a possibility that as a minimum needs to be addressed. The internal door may be an addition, so I may need to consider ventilation as well as DPC. I have no reason to suspect penetrating damp at the moment. Am I missing anything else? Thanks AB