Woodworking/construction Quiz For 3 June 04

[Ralph Jones]

Good Evening Friends,
When constructing a foundation that will support a brick veneer on a house or building.

What size foundation should you build?

Respectfully,

[craigb]

Is the brick venerial going to be on a slab or piers? You don't specify.

Mick will have the answer for both scenearios. I don't have a clue.

Mick?

[Ralph Jones]

Hello Mick,
The brick veneer is going to rest directly on the foundation itself.

Hope this clarifies it for you.

Respectfully,

[journeyman Mick]

Well it depends on: (a) your soil type and its bearing capacity, (b) the height of your wall (obviously a 2 story brick wall is going to require more footing depth than a single story wall and (c) how conservative the certifying engineer is.

After having said all that brick veneer on strip footings is very uncommon in my area as the closest major manufacturer of bricks is about 1000km away so freight is a bit of a killer. Most brick veneer is on raft slabs which generally have a 250mm wide by 300mm deep (including 100mm slab) thickening. I've only ever worked on one house that was brick veneer on strip footings. From memory it had 200mm wide footings 400 deep with 4-F8 TM 50BC hung vertically in the footing (that's 4 bars of 8mm Fabric(meaning welded together with cross bars) Trench Mesh, 50mm Bottom Cover). This was single story construction on well drained clay.

Actually looking back to the original question: "What size foundation should you build?" The simple answer is whatever the plans tell you to/the engineer has specified. (note: In Australia at any rate, a "footing" is a structure you place in the ground to support a building, a "foundation" is the ground that supports the footing).

Mick

[Ralph Jones]

Hi Mick,
Here in the USA a foundation is the materials used to build the walls of the foundation on the footings. The width of the footings must be twice the width of the foundation wall and 200mm to 300mm thick depending if you are using line block or 200mm poured concrete. Usually they might require two #5 steel rebars in the footings.

Soft clay will have a capacity of 1 ton per square foot.
Wet sand or firm clay will withstand 2 ton per square foot.
Fine dry sand will withstand 3 ton per square foot.
Hard, dry clay or coarse sand will withstand 4 Ton per square foot.
Gravel will withstand 6 ton per square foot.

The architect or engineer will need the soil sample of the area where a building is going to be built to determine what size footings to install.

Hope this clarifies a few things for you, pertaining to the USA and regional codes.

Respectfully,

[bitingmidge]

he architect or engineer will need the soil sample of the area where a building is going to be built to determine what size footings to install.

Not implying that we are over regulated or anything, but for the first 200 years of this country's history, there were a couple of standard size footings with standard reinforcement. For Cavity Brick the footing was 2'0" x 1'0" and for Brick Veneer 18" x 2'0" all to be founded a minimum of 2'0" below the ground or natural ground whichever was the greater. Reinforcement was one layer of trench mesh for single story, two for double!

There was this little book called "The Commonwealth Bank Acceptable Standards for Domestic Construction" which was the builder's bible.

If the ground was a bit gooey, you'd bung some piers under the footing and maybe a bit more reo, and mostly it was alright. In fact failures were not really any more prevalent than today.

Today...(in Qld at least) we must have an engineer conduct a soil test and certify the design and construction of any footing for any structure.

Result: Same size footings, more cost for the consumer, but everyone except engineers get to sleep at night without worries.

Since the advent of engineered design, (or the removal of guesswork) we have seen common use of narrower footings as described by Mick, which make things a bit easier to build so maybe there is some benefit after all!

Cheers,

P

[Ralph Jones]

Good Morning Friends,
I enjoyed your comments and you all are correct about the size and depths of the footings. Of course each local has their own way of understanding the codes and what might be OK in one area would not be accepted in another one.

So we all learn how things of the same methods have different allowances world wide.

Thank you for your support.

Respectfully,

[DaveInOz]

You should also bear in mind the size of any anti-union labor, or anyone else that needed too much persuading, no new home owner wants body parts poking out of their footings. Remember too many bodies in the one building can wreck the integrity of the footings, you don't want it to come tumbling down due to too many bodies and not enough reo!

Dave the blade.
Member of good standing of the Legitimate Businessmens Club. :eek:

[journeyman Mick]

Dave,
anyone who has a building come down because of too many/too large bodies in the footings is obviously using the wrong techniques. Industry standard is to bore a posthole 2M deeper than required and stand body in the bottom, this has the added advantage of enabling more bodies per M2 to be disposed of :eek: . However this technique has been all but discontinued as more of your fellow Legitimate Businessmens Club members are availing themselves of the services offered by treeloppers and their chippers :eek:

(sick)Mick