How do I work out where my damp proof course is?

[GarethSE5]

I have a ground floor flat in a Victorian (i think) terrace. There's damp in the exterior walls (mould, peeling paint), but not the interior walls. I've done a bit of research and think that the gravel in the back garden and the paving in the front might be 'bridging' the existing damp proof course because they raise the ground level above it.
I can see the air bricks, they are mostly clear of the gravel, but the gravel covers the bottom of them. Would the damp course be at the level of the bottom of the air bricks, or below them? Or is there another way to work out where it is, and whether this 'bridging' that i've read about is causing the damp?
I'm hoping to be able to sort out the damp problem without bringing in expensive specialists - but if anyone wants to tell me I'm barking up the wrong tree, I'd be glad to hear that too...
Thanks in advance for any advice.
Gareth

 

[handyman77]

Are you sure those air bricks arent for venting under the floor.
Check for about 100-150mm above ground level for slate in the pointing.
See if theres any holes been drilled for a liquid DPC.
Just because theres mould and peeling paint doesnt mean its rising damp.
Could be penetrating down from windows and sills. Check for gaps and cracks around windows and sills. Leaking gutters dont help if the dripping onto the sills. Could be from condensation, is there new windows.
Can be a lot of reaons. You need someone to check it out!
If you get a damp proofing company they without doubt are gonna recommend injecting a DPC regardless of whats causing the damp.
Investigate yourself first, maybe post some pictures.

 

[tony1851]

Victorian terrace houses didn't generally have damp-proof courses.

You will probably get a few plausible suggestions as to what it might be but unless you get someone to look at the problem properly you might go round in circles. It could well be what you suggested regarding the paving, but there may be other factors.

 

[handyman77]

Maybe in manchester they dont have damp courses in london they generally do!

 

[ei8htbuildingservices]

Sorry tony! Handyman is right,every house i have worked in has some form of damp course, otherwise they would all be damp.
There can be many causes of the damp as mentioned, try to pin point yourself before calling out an expensive firm.

 

[tony1851]

Sorry tony! Handyman is right,.

Thanks for that guys! I must confess I haven't worked (architecturally) further south than Wilmslow so wouldn't know how they did things elsewhere; presumably standards in the capital have always been higher than up here.

In general, though, even quite large detached houses here rarely have any form of dpc before the early 1900s. I have only ever seen one slate dpc many years ago - I even took a photo of it but can't find it now.

Perhaps in the old days, when coal was plentiful and the house kept warm by the constant fire in the range, rising damp might not have been such a problem: warm fabric + cellar + constant draught caused by the fire = dry house? Post-War heating methods (itermittent electric heating, paraffin stoves etc) could almost have been designed to encourage rising damp.

Thanks again; as the old Chinese proverb goes - 'better to be a fool for 5 minutes than a fool for the rest of your life'.

 

[maltaron]

Many Victorian and pre WW2 houses had blue brick or hard red engineering bricks for a damp course. Look for 2 courses of blues or reds that look denser than commons. If so, check that they are not bridged by soil anywhere, air bricks should be below or in the DPC.

 

[GarethSE5]

Are you sure those air bricks arent for venting under the floor.
Check for about 100-150mm above ground level for slate in the pointing.
See if theres any holes been drilled for a liquid DPC.
Just because theres mould and peeling paint doesnt mean its rising damp.
Could be penetrating down from windows and sills. Check for gaps and cracks around windows and sills. Leaking gutters dont help if the dripping onto the sills. Could be from condensation, is there new windows.
Can be a lot of reaons. You need someone to check it out!
If you get a damp proofing company they without doubt are gonna recommend injecting a DPC regardless of whats causing the damp.
Investigate yourself first, maybe post some pictures.

Thanks for this. The air bricks are at floor level or just below, yes, if that would mean what you suggest (I don't really understand, sorry). There's a band of concrete at floor level that the air bricks are set into.
There's no sign of slate in the pointing, or of holes drilled.
Some of the damp is under window sills, but some of it not near any obvious cause. It's all original sash windows, which look pretty intact inside and out, but there is a lot of condensation from time to time.
Looks like I'll need to get someone in, but any more ideas welcome. And yes, I'll be avoiding the damp-proofing companies until I know I need one.

 

[GarethSE5]

Many Victorian and pre WW2 houses had blue brick or hard red engineering bricks for a damp course. Look for 2 courses of blues or reds that look denser than commons. If so, check that they are not bridged by soil anywhere, air bricks should be below or in the DPC.

No sign of a different coloured course of bricks, no. Air bricks are in a band of concrete at ground/floor level, half obscured by gravel or paving.
Thanks, though. Any more ideas welcome.

 

[tim00]

Tony, with respect, for i've learned a lot from your posts. But Manchester builders did build-in some kind of DPC's into some housing stock going back into the mid 19th C. Slate, bitumen and engineering/dense brick were some of the materials used.

AAMOI: The whole issue of when DPC's were first installed, and where, doesn't seem to have been established by the architectural historians.
For a time the dating seems to have relied on various Blg. Regs. but there is much evidence for pre-dating the Regs. that first mention DPC's.

I'm going to post separately in the "Building Forum" on this issue and offer a "charity prize" for the best info. for dating DPC's.

 

[tony1851]

Manchester builders did build-in some kind of DPC's into some housing stock going back into the mid 19th C. .

Right; I'll crawl back under my stone now and keep quiet!

Seriously, I'll watch the dpc hunt with interest. i think the best source of info for early dpcs could be old copies of The Builder, dating back to the 1840s; we had copies in our old uni library, which were an almost inexhaustible mine of detail on old methods of construction.
Having the time to trawl through it, though, would be marvellous; too easy to get side-tracked as well.