Digging out under our house

[Arron]

Hi folks. The photo attached is underneath our house. Actually its 5 photos stitched together. Naturally the beams are straight, its the photography that makes them look bent. Anyway, I need more shed space and am thinking about digging this area out. I'd like to remove the nearest three piles on the right, which I think will give me enough space. The problem is I know very little about this. Can anyone give me some pointers to how this is done. Ultimately, I'll get a builder to do the structural stuff, but I like to know what is involved before I start talking to contractors.

I assume a beam or RSJ is slung across somehow, the piles are removed, the clay is dug out, a slab is laid and the walls are lined somehow. Any further detail, advice or clarification would be welcome.

thanks
Arron

[dallas]

Arron,

mate, i'm doing the exact same thing at the moment. Got builder to do the beams and excavations, and i'm gonna organise the slab and the rest of the fitout.. here's some info i put up recently:

http://www.woodworkforums.ubeaut.com.au/showthread.php?t=19875&page=1

a few things to consider:
- you'll prob have to put windows in (i'm gonna put in a combo of windows and glass bricks to give me light
- flooring? what flooring are you gonna use on it?
- yuo'll prob need a retaining wall around 300-500mm out from the existing footings around the excavated areas to hold back the dirt from under the footings...

beams have been notched into existing piers at the far ends of the span, and new piers have been bricked and tied into these piers to strengthen them.

if you have any other questions, let me know....


D

[Sturdee]

Any further detail, advice or clarification would be welcome.

thanks
Arron

Arron, I have done it. My workshop, both the main part and the back addition are dug out underneath my house.

I have timber stumps, not brick piers, and what I did was bolt either two steel RSJ's in the main part and two new timber bearers on either side of the existing bearers in the back addition. I then installed new stumps at both ends and then started removing the soil and existing stumps.

It is not difficult but time consuming. As I have solid clay under the house I used to hire an electric kanga for a few hours to loosen the clay and then shovel it out. This I did until there was room to swing a pick. It helps if you don't have to cart the soil away but can use it in the garden. I filled an old swimming pool and then levelled the back which was on a slope.

Make sure there is adequate drainage provided before pouring a slab and retaining walls. The surface may seem dry now but you may get a drainage problem if you start excavating. It is also best to leave it dug out for a while to check for this.

Because it is under the house it is essential to install a ceiling with soundproofing. Every noise you make can otherwise be heard upstairs and vice versa. I used masonite with insulation bats in the main part and soundproving ceiling tiles in the back part.

Make the depth adequate for your future needs. I thought I went deep enough but if I had gone a bit deeper I could have used 6" DC ducting instead of the 4" I had to use. Ofcourse when I started DC's for home workshops were not yet available.

Finally, I have no windows in mine so I painted everything white and installed sufficient lighting to make up for this and an extra wide door would also be helpful to get things in amd out.

Good luck and let us know how you get on.


Peter.

[tcns]

Arron, I have done it. My workshop, both the main part and the back addition are dug out underneath my house.

I have timber stumps, not brick piers, and what I did was bolt either two steel RSJ's in the main part and two new timber bearers on either side of the existing bearers in the back addition. I then installed new stumps at both ends and then started removing the soil and existing stumps.


Peter.

Peter,

This is good info, I have a very similar setup at home. Now, I have been trying to picture how you have done this and well, I guess TV has nearly runined my imagination, any chance of a quick mud map of the rsj and existing beams. Also when you replaced the stumps on the end/outside did you upgrade them to cope with the increased stress on them.

I have a garage under my house that is next to uselss with the piers that are there, I virtually have 2m hight at best down to 300mm - I really want to dig it all out to 2.7m - I know i have retaining walls and new driveway requirements but that is far outweighted by the additional space and usability.

Any further info would be great thanks

Cheers mate
Tom

[Sturdee]

Tom,

Altogether I have removed 10 stumps in 5 places to make my workshop. The first lot was done more than 20 years ago and the last lot about 4 years ago.

I'm planning to remove 2 more to enlarge and improve the space for the DC setup so that I can excavate enough to create space for a cyclone instead of the drum separator.

I'll take some measurements and sizes tomorrow and post the details but for photos you'll have to wait 2 weeks. SWMBO has gone on her annual holidays to visit her parents up north and has taken the camera.

Safety message - Whilst I'm happy to post details on how and what I have done I suggest you get an engineer to check what you are intending to do for each house is different and may have different load bearings and stresses etc. In other words don't assume what I've done will suit you - End of safety message.


Peter.

[tcns]

Tom,



Safety message - Whilst I'm happy to post details on how and what I have done I suggest you get an engineer to check what you are intending to do for each house is different and may have different load bearings and stresses etc. In other words don't assume what I've done will suit you - End of safety message.


Peter.
Thanks Sturdee

I will consult with an engineer and I would appreciate the photos when you get your camera back

Tom

[choeffie]

I hvae reviewed some of the responces to your posting. I am looking at doing virtually the same thing as yourself. I have a queenslander that is currently raised with a stepped concrete slab underneath. My property falls away as well but probably not as extremely as yours. My slab step is around 500mm to take this slope into account. For some reason, whoever raised the house decided to raise it so that there was only 2200mm clear to the underside of the floor joists (approximately 2000mm to the underside of the beams). The other section of the slab is a further 500mm lower, hence no real problems for building in underneath. I am a novice at this and would like to know if anybody has come across a similar circumstance. What is the legal height for houses ? Is it 2400mm clear?

Your advice would be much appreciated.

[journeyman Mick]

Choeffie,
from memory, bedrooms, lounge, dining and all "living" areas need minimum 2400. Bathrooms, laundries, kitchens and hallways 2100. This may all have changed (I don't try to keep up anymore) so ring your local council's building department.

Mick

[TritonJapan]

Aaron,

I went through the process of speaking to designers and builders about a very similar thing, to a larger scale.

As I wanted to get the most space I could under our house at the time (Ringwood Victoria) I was going to underpin, take the walls straight down, instead of retaining walls 1 m in from the exsisting ones.

It looked as though I would just miss out on the height requirements, unless I became the lowest point in the street, which would have made the frogs happy.

Then started looking at the option of jacking the whole house up. Recall seeing an article in one of the local papers about a guy who was doing it.

Being brick veneer, then decided to lose the bricks, as they were pretty ugly, which would make the whole job a lot easier.

In the end, I moved to Japan. Much cheaper!

No help what so ever really, but it was a great time, looking at the possibilities of a large, sound proof workshop, billard room, cellar, bar, home cinema, kids retreat, garage.

Though the quotes were getting high, I still felt it was better value doing this to an old house on a big block and end up with a huge house as I wanted it and still keep the back yard. For the same price as the house and renovations / re-build, could get a brand new box, with no yard but some fancy foam cornice in the entry hall.

Some of the regulations to watch were the ratio of windows to floor space, I think was about 10:1

After living in Japan for a while, I now value the back yard more than ever before. If you can make use of the space under the house, go for it!

Steve

[choeffie]

Thanks for that Mick. Sorry for tagging onto somebody elses 'thread'. I don't know how to start my own query/posting. Can you help me with that?

[journeyman Mick]

choeffie,
go to the top of this page
click on woodwork forums
go to the forum you wish to post in (ie Home Renovations)
click on "post new thread" (I think that's the name of the button)
follow the prompts

Mick