Saturday, August 16, 2014

Stepped Strip footing

To watch the video on this subject go to “Stepped Footing”

When we have a block that is not level we can either level the block or we can work with it.

To work with the slope we need to step the footing down the block so that it remains in the ground. This will mean that we will have to start the footing lower in the ground and then when they get to around 1 course of brickwork (86mm) from the surface then we need to step down.

Each step should be made so it works what ever you are going to use for the Dwarf wall. For example with a standard metric brick you can step down 2 courses (172mm) at each step so that the bricklayer won't have to cut a brick lengthways to suit the step.

Remembering that we need to maintain a minimum of 400mm under our bearer this will set the minimum height of our dwarf wall.

The changes in heights won’t affect our engaged piers as they are tied to our Dwarf wall.

However we will need to keep an eye on our Isolated piers. A 230 x 230 pier (1 bricks x 1 Bricks) can only be a maximum of 1 metre high.

Once it reaches a metre the size of the base needs to be increased to 350 x 350 (1.5 bricks x 1.5 bricks). Once the pier gets to this size it would be worth looking at other options such as steel as a more economical option.

With the Dwarf Wall constructed we now have a level base on which to construct our Floor Frame.

Friday, August 15, 2014

Stair Components and Terminology

To watch the video on this subject go to ‘Stair Components and Terminology’

Rise Of Flight
The rise of flight is the vertical distance between the finished floor levels (F.F.L) or landings.

Going of Flight
This is the horizontal distance from the face of the first Riser to the face of the last Riser.

String or Stringer
Designed to carry the load of the stairs, there can be 1, 2 or even 3 for wide stairs. They normally form the side of the stairs however they can also be placed underneath.

The part that you step on.

The Riser or Riserboard closes the gap between the Treads. Normally omitted in External or Industrial stairs.

Newel Post
This is the upright post attached to the Stringer which supports the Handrail.

Runs Parallel to the Stringer a minimum of 865mm vertically from the margin line. It provides support for the users.

The vertical members that fill in the space between the Handrail and the Stringer.

This is the Handrail, Balusters, Newel Posts and other components that form the Handrail combined.

Rise of Step

This is the distance from the top pf one Tread to the top of the next.

Going of Step
This is the distance from the front on one tread to the front of the next.

This is the distance from the edge of the stringer to the point of the treads.

Tie Rods
Used to tie the stringers together so they don't separate over time. Spaced every 1350mm along the length of the Stringer.

Saturday, August 9, 2014

Backfill a Retaining Wall

To watch the video on this subject got to “Backfill a Retaining wall”

The design of a retaining wall is usually the responsibility of a structural engineer or you need to use a patented wall system so I am not going to talk about the wall itself rather what we need to do when we backfill.

If we were just to backfill hard up against the wall with the existing soil on the site or imported soil there is the chance that, in wet conditions, water will build up behind the wall and increase the weight of the soil acting on the wall. This is especially true if the wall system doesn’t let water pass through it.

So at the bottom of the wall we need to have a way for water to get around the wall. This is achieved by bedding a Agricultural Pipe ( Ag Pipe) in approx 50mm of sand. The pipe should be connected to the stormwater system or into an appropriate drain.

On top of the pipe we need a well draining material such as blue metal or recycled crushed concrete. This will need to be added in as the site is filled.

We also need to make sure that our well draining material doesn’t become clogged with the soil from the rest of the site over time. This can be achieved by placing a Geotech fabric between the two materials.

A couple of 100mm from the top you should finish the well draining material, put in a layer of Geo-tech and then cover with topsoil so everything is hidden.

Now we have a system that we ensure that our Retaining wall is only exposed to the loads that it was designed for and excess water is diverted to where it can’t do any  damage.