Internal and External Floor Levels

[hankmarvin]

What I have agreed so far with BC is that my dpc will be one course lower under the bi-folds which will give me a minimum sill inside.

But they also said I need to maintain a 150mm under the bi-fold, which is fine, I have room, but it means I have that size step outside onto future patio most likely.

Could the ground be higher under the bi-folds as any water splash back will only hit the glazing...?


How do other people with bi-folds get away with similar internal and external levels.



And if you go for a sill without one of those sloped drip tray things the water runs down glass and the internal channel also and straight onto dpc, what's to stop the water pooling on that edge and seeping back under the sill into your cavity?


Any thoughts would be great before I ring BC again.


Thanks
Hank

 

[hankmarvin]

BC said I could have a higher external floor level if I used a cavity tray, a double dpc or a 10mm slit drain across the front of bi-folds and then start the patio 100mm away from that.

Other options were a roof overhang or a pea shingle trench in front of the doors 150mm wide and then start the patio but he was less keen on them.


Is the below the basics of a double DPC?

____top DPC_____| bi-folds bi folds bi folds bi folds |______top DPC_______

DPC-----------------|_____bi-fold-DPC___________|------------------DPC
---------------ground level - closer to main dpc than 150mm------------------



A cavity tray would be dpm material bedded into the internal skin and then be bedded into external dpc creating a diagonal between higher point internally and lower point externally?


They both sound cheaper then running a drain at the front.

 

[themiddleagedun]

Use 2 DPC's, one at paving/threshold level, the other 2 brick course higher. Obviously slope the paving away from the door slightly.

A cavity tray is a non-starter. A 100mm gravel strip between the house and paving might keep BC happy... and looks quite smart anyway IMO.

BTW Loved Apache

 

[hankmarvin]

top tune

Yeah I think I will go for a double dpc, patio will be aimed at just under dpc/bi-fold sill drip edge, then as you say a second dpc 2 course up and I'll still a pea shingle trench down too, BC should be happy.

Would I have to follow this second dpc around the sides too, or just on side the bi-folds are?

 

[themiddleagedun]

Everywhere were the paving is less than 150mm down from the floor level.

 

[hankmarvin]

excellent, thanks very much.