When you are converting the loft the waste pipes should be fitted during the first fix plumbing stage and, thanks to modern materials and products, they are pretty easy to install.
A bathroom loft conversion usually accompanies the creation of new bedrooms in the roof space to provide en-suite bathroom facilities.
An important thing to get right in the planning stage of a bathroom is its location.
Getting it right will pay big dividends later on.
The ideal location is as close to the existing second floor bathroom as possible. Doing this will ensure that the new waste pipes from the loft only have a short way to travel before linking up with the existing soil and vent pipe.
As we said in the opening paragraph the new white plastic push to fit pipes are very easy to use and install but you must be aware of the problems of siphonage.
This happens when the 'run' of the waste pipes is too long and can cause unpleasant smells.
The way to avoid siphonage is to make sure the length of the waste pipes are kept as short as possible and in fact the building regulations are specific about the maximum length of the pipes.
However, even if there problems than simply using a bigger bore pipe can often get rid of them.
One other thing that needs to be considered is the existing soil and vent pipe.
The usual rule for the soil and vent pipes in UK housing is for the pipe to be boxed in before exiting through the roof. The building regulations insist that the pipe should be positioned at least three metres away from any windows.
This isn't a problem until new skylight windows are installed during a loft conversion.
In this case the soil and vent pipe can simply be extended to maintain the required distance though in many instances the old pipes will need to be replaced with more modern plastic piping.
For more info see the related pages below
Vermiculite Loft Insulation is an echo-friendly alternative to traditional insulation materials
The old loft water tank will need to be moved if the roof space is being converted into a habitable room
Structural calculations for loft conversions are of course hugely important to ensure safety and that the proposed plans meet building regulations