So.... After not having a porch on our house I built a temporary shelter till we saved up to build a 3m x 1m porch (no planning needed).

So I built this....



It's ok for now, but miraculously we got planning for this...



Which is great, but hence the sale of the School Bus. We got quoted around 10k all in, which was ok until I spent a lot more that I had planned on the new Bug...

So.... My question is this..... Is there any good guides to starting foundations for something like this? I have googled porch (they seem to be too small) then single storey extension... But that's too much with building regs, insulating floors etc as all I have found on single storey extensions are classed as rooms. This will not be classed as a habital room as the existing outer door, window etc on the existing build will remain, there will be no radiator etc also...

So I'm needing info on what the foundations need to be (depending on foundations under the house of course) so I can try and make some money back on the money I've spent on the bug!!!

Any help or links would be great.

Cheers.

Suggest 600mm wide, founded 1000mm below the existing ground level with 700mm depth of concrete, all subject to building control approval

Not a bad starting point Ziggy but it will depend on existing footings too. I did a job where we hit solid chalk at 500mm and as that was the house foundation it was fine at that. Another job had 13m piles on all corners and 11 m piles in the centres due to that being what the existing foundations were due to ground conditions.
It's as flexi as a bus build lol
Neil

Ok, so first point is to see how far the house foundations go down.

There will be no weight on the new walls apart from the roof which hopefully will be as much glass as possible.

As for the foundations, I only have to dig down where the new bricks will be, 600mm wide and X deep. The rest of the interior floor is up to me?

Cheers guys.

So the floor area is commonly called the oversite

I suggest...

150mm compacted and blinded hardcore sub base
1200 Guage polythene damp proof membrane, dressed up to the perimeters into the wall DPC
100mm thick in-situ concrete slab
100mm thick floor insulation with 25mm thick vertical upstands to the perimeters
65mm sand/cement floor screed

All you will need then is to lay your chosen floor covering

Hi Sooty,

Don't know if I missed it but you have planning permission but do you need building regs? If you do then the building inspector will tell you exactly what you need, or should I say, what he wants. Don't be afraid to ask them, they're there to help.

If you don't need building regs then as for foundations the golden rule I use is copy the house foundations. And as regards the slab etc then Ziggy is correct although I feel the 65mm floor screed is overkill and not needed. And to be exact the visqueen should go under the floor insulation and another layer of visqueen before the slab

Just noticed you've got suspended floors, correct? If you're planning a concrete floor and you're going to block up an existing air brick then you'd need to duct that out, not a complicated job but will need doing.
You're porch really isn't that big a job, i'm sure you'll be able to save on the original quote

Wow, cheers guys.

I've got planning passed but as I'm not knocking the rooms together and I'm keeping the existing front window and door... And also I'm not having central heating in there apparently I don't need building regs

So I was led to believe.

Cheers.

Oh and the air brick will be still open and will be coming into the new porch. The base of the porch (the floor) must be as low as possible so the start of the roof is as low as possible to the house. So with the angles the roof doesn't end up going into the upstairs window.

Does that make sense?

I will build steps inside the porch up to the front door.

I would of thought you'd want the floor of the new porch to be same as existing internal as it keeps things open for the future of opening it up to a big entrance hall Pitch of roof doesn't look a problem at all to me either judging by the drawings.

It's all one room as it is mate, unfortunately when you open the front door your straight into our kitchen/diner. We knocked through the garage, raised the floor and built a lovely open kitchen diner type thing.
Problem is, the front of our house get a right hammering from weather so rain comes in, wind howles through tiny gaps.... Hence why the new door is on the side!

Inside will be a utility with the W/M T/D, coats, shoes, bags.... All the cr#p you get with a family... So we can free all the cupboard space in the kitchen diner.

All the white goods will be hidden in cupboards, counter tops in wood.... All the coats in sliding wardrobe type thing at far right (hence why no window there) and all shoe racks made into shelves under another wooden counter under the window.

2 front doors.... Double security and also make our house a little warmer!

Well.... That's what's in my head!

If the floor was the same height as the internal floor we would have to put a flat roof on as the new outside door would be say 18 inches higher that the diagram shows.

It's hard to tell but if you look at the existing photo, you step onto the decking (deck board height) and then step up another one just to get to step through the existing front door.

The bottom of the existing front door is about 18" from the level of the pebbles.

Ah ok, I get it, just looked like the new porch window looked the same height as the existing front window but if it'd be used as you've said then its not worth even thinking about trying to make floor levels work

Yes, the new front window will be the same level as the existing large one to the left. Notice on the photo the kitchen window on the right is higher than the left one!

The only downside is the view from the kitchen will be restricted by the start of the new roof.

That's why I put the glass a foot higher than the tiled roof to the side so the gutter wasn't at eye level.