Weep holes internal

[trevorbayliss]

In the photo you can see i have my foundation block level and then a brick course and on top of this will go the breeze block level which will be the level of my new suspended floor in timber.

I have a 22cm drainage channel behind the breeze block which i think you need.

Now my question is should i put in a few weep holes in this breeze block course ? Any water would just drain out below the joists and onto a screed of concrete blinding which i have to lay.

Also do i lay my DPC below this breeze block course. The external DPC is going to be two brick course higher on the external leaf. Is it ok to make them different levels or do you make them the same.

 

[Blagard]

Now my question is should i put in a few weep holes in this breeze block course ?

No

Also do i lay my DPC below this breeze block course ?

I would lay it at the same level as your hangers, top of the breeze blocks

 

[John D v2.0]

You don't want weep holes to inside, you need to slope outwards and have the weep holes there

 

[^woody^]

I have a 22cm drainage channel behind the breeze block which i think you need.

What does this mean?

 

[^woody^]

Why are you venting on the side of the building instead of the rear elevation?

 

[trevorbayliss]

Looking at the regs you need to have a minimum depth in the cavity for drainage.

http://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2011/Part5/section1/sitework.htm

So it means i don't fill this cavity with concrete as i have done on the first course below this course.

I am venting side to side because our house has a solid concrete floor downstairs and i didn't want to do concrete for the extension. So to get air flow i have to go side to side.

 

[John D v2.0]

The clear cavity is to stop water splashing back up over the dpc on the inner leaf. You still should to slope it to the outside. In ours they bodged it and used a strip of dpc as a cavity tray but with hardly any slope. The architect said it would just about do as the outside face is rendered.
Just the main principle is make sure all water is directed outwards and any cavities with timber are ventilated, and anywhere water can splash to is below any dpc.

 

[trevorbayliss]

At the moment i am still below ground level. So is your slope draining into ground or is this above ground? If everything is below ground how does the water in the cavity push out through the external brick and into the surrounding earth ?

 

[John D v2.0]

Drains into the ground, unless your water table is high it should escape. If you direct it inwards, it is less likely to drain through your over site as it will have a dpm somewhere in the buildup, so better to go out. Your over site should be above ground level or drained if possible, but our architect didn't seem worried about it.
If that wall gets a lot of weather and is unrendered you could always put in a cavity tray just above external ground level.

 

[trevorbayliss]

We are pretty protected here. One wall will not get any weather as it is next 450mm away from a large garden wall.

Our ground is also very well drained as on sand, so that is a plus. Because i am doing a suspended floor, my void under the extension is going to just have 50mm of concrete over it. BC has said this is ok. He may ask for a membrane, but so far hasn't. I am seeing him this week so he will tell me what he wants and i will check if i need the membrane.