Carpentry

The carpentry or carpenters element of work is quite detailed and would be broken down into the various sections for costings. These cost headings are often carried out as an individual task, and contain the elements of work as descibed below

 

• Floor Joists

  As your extension comes out of the ground, it will soon reach a height where by the windows will be put in, or holes left or dummy frames fitted that can be taken out and repalced when the proper windows are ready.

  Over the windows the bricklayer will build in lintols, these are structural and are designed to support the weight of the biulidng over the window, which without a lintol would crush the window. On a single storey extension the roof would then be added, but on a double storey extension, the floor joists will then the installed by the carpenter. The height of these is very important, and should be worked out carefully, with the help of the bricklayer and carpenter - the top of your floor joists, allowing for the flooring to be fixed on top must match the same level as your existing floor, as you dont want a 'step' into your new extension.

  Floor joist are a structural part of your building and calculations, most often provided by a structural engineer will need to be carried out and submitted to building control for bulding regs approval. Floor joists are often timber, and selected and graded for their structural properties, and cut to lengths and sizes dependant on the spans and weights they are required to support. In recent years 'engineered' joists have become more popular, these are manufactured I joists, and are lighter, but structuraly made.

  Your carpenter will put struts between the joists to stop them from twisting.

• Main Roof

  In extension construction there are usually two main types of roof, a flat roof and pitched. Constructing the roof is also referred to as the roof carcass.

  Firstly we will explain the flat roof. Constructed from a carpenters perspective it is very similar to floor joists, the materials used are the same, structural, with a solid deck overlaid to take the waterproof asphalt topping, with a barge board and a vent strip. Firrings are often then laid on top of the joists to provide a slight slope top the roof to allow the water to drain away.

  A typical pitched roof layout for a house

  

  Pitched roofs are generally more preferred, but planning restrictions can mean they are not always permissible.

  Depending on the size of your roof, the two main types of construction that could be used are cut and pitch or trussed rafters. Both methods can be used for a roof, whether your roof design is a traditional pitched roof with a ridge to it, or a mono pitch.

  Cut and Pitch Roof - If the roof is small or the complicated, or both!, then the roof will usually be constructed in this way - and it is as it says, the carpenter will get the timber requried and then cut them to the correct lengths and fix them in their pitched positions. If you have dormer roofs being fitted this will nearly always be constructed in this way. It is a longer method of construction, but often the best way of achieving what is on the plan. As with floor joists, the sizes of timbers used will usually be calculated by a structural engineer, and passed off by building control.

  Trussed Rafters - These are constructed off site, in a factory. The calculations are done and designed before they are made, and these can then be submitted to the building officer as part of the building regulation approval. The timbers will often be smaller than in a cut and pitch roof, but are designed that way, and are not designed to be cut or altered on site. Due to the spans they have to cover, they are often quite large and a crane can be required to lift them into position - this is a question your builder or carpenter will ba able to answer, and for them to quote accordingly to included this hire and liasing to get the crane to site at the correct time.

• Low Level / Porch Roof

  These are often constructed toward the end of a project, when the scaffold is down so that access can be easier, as well as making sure that the scaffold does not knock or damage them when they are built.

  As with a main roof, they can be trussed or cut and pitch. Usually only a small span, but if the porch roof is bolted onto the outside, then it is important not to drop or add excessive weight to the structure.

  

• 1st fix

  The carpenter will also be busy at the 1st fix stage, they are used to working in conjunction with electrician and plumber and they be required to install battens, or fixing panels for sanitaryware or other heavy fittings that require screwing. The carpenter will erect stud partitions, fix window boards, fix door linings, fix a loft hatch, fixing ceiling and floor battens for fixing floor boards or plasterboard to ceilings. At this stage the carpenter should also fix any external doors. If a two stoery extension is being built, the main staircase (no balustrading or handrails) will be installed at this stage.

• 2nd fix

  The second fix carpntry incudes

• Finals
• Kitchen installation
• External doors & windows