At the Barratts site, timber joists are used to form the upper floor.

Generally, Barratts use joists sized 50mm wide and 200mm depth. A beam of this depth can span 4230mm.

They are placed parallel to each other at 400mm centres (because the joists are 50mm they will actually be 350mm between one another). This is the most economical method. If the joists were spaced any further apart they would require a deeper depth, and also the actual floorboards above would need to be deeper because of the extra span.

Although a traditional technique, it would be better to use galvanised steel herring bone strutting which are small struts crossing each other which are and attached to the joist. The solid timber filled strutting is susceptable to problems. If the timber shrinks the strutting will detach from the joists and will no longer give lateral support. Therefore the floor will fail. Whereas a steel herringbone strut provides complete lateral support where no shrinkage can occur, hence no floor failure.

By using solid strutting there is no room for cables to run, unlike herringbone where there is plenty of space.

Barratts have had to drill holes into the joists to allow electric cables to run through, thus weakening the joist itself. (see photo)

Barratts use a variety of techniques for fixing the joists to the internal leaves. Different techniques are used on different walls.

For instance, in non-party walls, Barratts build the joists into the internal blockwork leaf of the cavity wall. However, there is a danger of damp penetration to the joists,which may cause rot, so to counteract this Barratts have built a course of blue engineering bricks into the blockwork to stop any damp penetration. The bricks are very expensive as they are very dense, and have a low level of water absorption so they are not often used. The bricks also have a high compressive strength which also helps the wall take the load of the upper floor.

For party walls, Barratts have used a different technique. Joists cannot be built into a party wall because of fire penetration and reduction of sound insulation. Therefore Barratts use galvanised steel hangers to support the joists.

Blockwork is built as normal up to the first floor level, with a course of engineering brick as before. Metal hangers are placed at the 400mm centres from the blockwork and the joists are placed into the hangers. For the joists to fit into the hangers they are notched slighty. Blocks are then laid onto the hangers as in a normal leaf.

Most joists won't actually span from one external leaf to the other, so internal wall support is required. When joists span over a internal wall Barratts use another technique to fix them.

The joists from each external leaf overlap on the internal wall where they are nailed to each other (as seen in the photo adjacent).

A timber wall plate is usually used beneath the joists to maintain the correct level, but as in this case, if the loadbearing internal wall is continued up into the upper floor then the wall plate is not required.

Some parts of the upper floors will need openings, especially for staircases. The joists have to be specially placed with extra support to form the opening, this is known as trimming.

Either side of the opening Barratts have doubled up the joists and nailed them together to gain extra strength, these are known as trimming joists. at the width of the opening a trimmer joist is placed, supported by the trimming joists. Barratts have also doubled these up for extra strength again, although this is not neccessary.

The joists running parallel to the trimming joists are fixed to the trimmed joist and they are known as trimmed joists. (Quite confusing!) They are all joined together by using 'timber to timber' hangers (as seen in photo).

In the opening on the above photo, a staircase will be fitted, like the one adjacent. In this particular Barratts property the easiest staircase design is used; a straight flight.

The staircase spans from the ground floor up to the upper floor by fixing horizontal treads and vertical risers to strings.

The treads and risers slot into grooves in the strings. Here the inner string is fixed to the wall and the outer string will eventually have a balustrade fitted supported by the newel posts to prevent falling.

More details on stairs and handrails follow in the Westermans section.

At the Westermans site, timber joists are also used to form the upper floor.

Like Barratts,Westermans use joists sized 50mm wide and 200mm depth. They are again placed parallel to each other at 400mm centres, because of economy.

At the Westermans site I noticed that for non-party walls, the joists were built into the blockwork. Unlike Barratts though, Westermans have not laid a course of engineering bricks into the blockwork, therefore damp penetration may occur (see alongside).

For party walls I was unable to find an example of fixing joists to the blockwork. However, because joists cannot be built into a party wall because of fire penetration and reduction of sound insulation, I would presume that Westermans would be using the same method as Barratts; galvanised steel hangers to support the joists.

Westermans also use the same technique of overlapping joists at internal walls. Again, no timber wall plate is used as the wall is continued into the upper floor.

The Westermans staircase shown opposite is also a straight flight.

Again the treads and risers slot into grooves in the strings, and are supported underneath with small timber blocks and a carriage. The inner string is fixed to the wall and the outer string will be fitted with a balustrade.

The staircase width is approximately 900mm with 13 risers at a depth of 196mm each, whilst the treads are 225mm. Therefore giving a pitch of approximately 40°, which is within the 42° building regulations. Headroom of 2000mm minimum is allowed

A handrail is fitted between 900-1000mm above the pitch line, and balusters are placed at 99mm intervals to stop babies from getting their heads through them, again in line with regulations. The handrail is fixed to newel posts at the top and bottom of the stairway for support. (All shown below)