Inside out space - DPC implications

MrDerp

Hi folks, hoping someone can let me know if there's implications to a concept we're looking at for our place.

We want to create and inside-outside space from our living room with tiles, but I have some concerns about the implications for damp proofing.

The current situation is:

1. Our living room faces the front, side and back of the house
2. There is a suspended floor installed in the living room
3. The outside space steps down below the DPC on all sides, with a raised deck at the back and side bringing the level up to the door.
4. House is timber frame with block outside and panels inside walls.

For heat and aesthetic purposes, we want to re-imagine this space to:

1. Replace the suspended wood floor with concrete and tile living room area
2. Replace some current French doors with a large bi-fold to open outside space
3. Bring up the level of the outside (with concrete) to create an inside-outside space with the same tile as the living room

My concerns are:

1. Do we need to be careful with venting the block cavity below the DPC? Currently this is vented through for the suspended floor.
2. I'm guessing we can't simply raise the outside level around the house above the DPC without consequences, but we could possibly do this, for example, to just the side?
3. Anything basic I'm not thinking about?

The natural grade of the site is towards the front of the house, and the storm flow goes down a sloped drive with a couple of sumps installed. I'm assuming the perimeter drains and proposed outside platform will need consideration, and that a good contractor will include this. The storm and sewer need work anyway (we know from a survey before we moved in) so we're not afraid to dig up the drive to put in a big sump and/or widened storm pipes if the extra outside tiled/concrete area demands it.

Calahonda52

Edit the title to inside out space

Changing the front of house will require planning.
remains floor will need to be vented, ensuring NO risk of flooding through the vents, given the sloping nature of the garden.

consider a driveway channel drain, making sure plenty of outflow capacity/ good fall/ easy to clean
https://www.drainage.nz/why-do-you-need-a-driveway-channel

rainwater smashing on the tiles outside on the wall above the dpc is a consideration

MrDerp

Calahonda52 wrote: »

Edit the title to inside out space

Changing the front of house will require planning.
remains floor will need to be vented, ensuring NO risk of flooding through the vents, given the sloping nature of the garden.

consider a driveway channel drain, making sure plenty of outflow capacity/ good fall/ easy to clean
https://www.drainage.nz/why-do-you-need-a-driveway-channel

rainwater smashing on the tiles outside on the wall above the dpc is a consideration

Thanks, title updated.

We won't be changing the front of the house, the concrete path in front will remain 15cm below the DPC. I should have said also, only this living room has a suspended floor - the rest of the downstairs funnily enough has a standard concrete floor. The house was built in '99 so the suspended floor in the living room is a rather odd standalone feature as is. Think of it as 1/3 of the floor area.

When I saw the garden is sloped, I mean from the front of the house down, though there's a raised area to the back of the house which would have some run-off.

Definitely considering the channel drain, I actually want to lay some concrete on the unmentioned side of the house for a parking area (currently footpath, a small concrete patch and a flower bed) - below the DPC this time - and had figured on a channel drain between the existing footpath and the new pour to ensure run-off is well drained.

So the DPC would remain 15cm+ above the ground path in front and to one side of the house anyway, but I'm thinking we would keep the raised deck out the back of the house - or a step down to concrete below the DPC if we must be solid there.

That just leaves the side with the tiles, and a risk of water splashing and pooling above the DPC line. Probably not a good idea to lay concrete along the width (~8.5m) here then. We should probably consider a deep channel drain here then, at the DPC, along the wall?

Appreciate the reply, thanks.