The Brew Cabin

Posted: **Mon Aug 30, 2010 10:36 pm**

I wonder if someone could clarify for me where exactly the 150mm between DPC and ground is measured when the DPC is a number of courses of blue bricks (1930s property). Is the measurement to be taken from top line or bottom line of the DPC brick courses?

I intend to lay a patio as close to the house and conservatory as possible. Conservatory has 2 courses of DPC bricks, House has 3 courses. Wondering if I need to install a dry area channel or if I can butt the flags up to the blue bricks.

Thanks in advance.

Posted: **Mon Aug 30, 2010 10:54 pm**

them theres big pictures matt!!

microsoft jpegresizer is your friend for forums

your slabs need to finish level with the top of that gully out side your conservatory
bit more digging I'm afraid mate
LLL

Posted: **Tue Aug 31, 2010 8:46 pm**

Ouch, aren't they just! Sorry, posted straight from my phone. Will look into adjusting!

Thanks for the reply.

I wouldn't go by the gully as a reference necessarily. I put that in myself. It's about 1" from the bottom of the DPC. The intention of building up any difference in level with patio with a tapered 'walls' of cement if needbe.

I'm expecting to skim the soil back for hardcore, sand then flags. My main query is if the flags can meet the bottom of the DPC.

I thought I did my research. Evidently wasn't thorough enough!

Thanks

Matt

Posted: **Tue Aug 31, 2010 8:57 pm**

As LLL says using the gully as your level is as good as you'll get. Any lower and you'll expose the blockwork. If the water is falling towards the house then you'll need a linear channel to keep things right. Because it's a conservatory and if you use a linear channel you could use the bottom of the 2nd brick as your finished level it's the only way of getting a neat finish without plastering.

Posted: **Tue Aug 31, 2010 10:32 pm**

Thanks Pablo, thanks LLL. Images adjusted!

The patio will fall away from the house. So, am I within regs/good practice for the flags to touch the DPC bricks as long as they are 150mm lower than top of the highest course of blue bricks?

Thanks

Posted: **Tue Aug 31, 2010 10:33 pm**

PS If anyone's using a mac for images, I highly recommend using Skitch. Image adjusting and hosting all in one.

Posted: **Wed Sep 01, 2010 12:17 am**

MattHogan wrote:Thanks Pablo, thanks LLL. Images adjusted!

The patio will fall away from the house. So, am I within regs/good practice for the flags to touch the DPC bricks as long as they are 150mm lower than top of the highest course of blue bricks?

Thanks

Can you see or do you know where the dpc membrane is.
As long as the finished height of the patio is 150mm below the membrane then you are ok.

Posted: **Wed Sep 01, 2010 7:10 am**

generally matt your conservatory will be sitting on the dpc , with the 2 course of blue staffs used as bricks that wont degrade
pls dont talk about laying slabs on sand here
slabs are laid on a beding layer which will include cement and water
its all in the main site matt
LLL

Posted: **Sun Sep 05, 2010 4:38 pm**

Thanks Bob_A and again, LLL.

It looks like the conservatory doesn't have a membrane at all! Which probably explains some of the damp rot in the timbers. I'm not surprised as whoever fitted it evidently made a catalogue of errors - shan't list here!

I can't and don't expect to see a membrane on the 1930s house which has, as I understand it, uses the 3 blue brick low absorption courses. Which led to my opening question.

So now to figure how I can insert a DPC membrane retrospectively in the conservatory...

Matt

PS, LLL, sorry for the faux pas! Rest assured, I laid natural stone patio flags some years ago which were on a bed of cement. Just out of practice talking about it

Posted: **Sun Sep 05, 2010 7:40 pm**

matt DPC and DPM are 2 different things
DPC is the material that stops damp rising through the brickwork
DPM is the membrane that stops damp coming through the floor
dpm can be applied retroactively by applying 3 coats of synthaprufe
your slabs should be 150mm below finished floor level in the absence of A dpc
cheers
LLL

Posted: **Sun Sep 05, 2010 8:47 pm**

Thank you very much indeed! Really appreciate your time and advice.

The Brew Cabin

Ground level from 2-3 brick dpc - 150mm from where?