Thinking of converting your attic? Well there are a few things to be considered, first up is planning and fire regulations. An architect or engineer can help advise for particular cases as the regulations depend on the existing house construction and proposed plans. Useful guides are as follows:Useful attic conversion guides:
Ireland – Loft conversions planning
England – Loft conversions, KDC
With respect to the engineering there are a few things to consider:
- Ensure the attic conversion is designed by an engineer. A builder and architect can convert an attic for you but to ensure it is safe you will need an engineer’s certificate. The best way to do this is for the engineer to design the scheme, using the architects drawings, and carry out an inspection of the structure prior to it being finished, and hidden behind plasterboard and floorboards. I have been in the situation a few times where home owners have contacted my to certify an attic conversion after it was constructed, but I couldn’t, as it was unsafe. In one of these cases it was the previous owner that converted the attic but left the current owner with the dangerous structure.
- If buying a house with a converted attic ensure you obtain the engineers and architects certificate for the attic conversion. These certificates need to confirm that the attic conversion has been designed and constructed to comply with the current building regulations, fire regulations and planning laws. If they are not available it’s not a good sign, but you could still get an engineer to check the attic out for you. The problem with this is that it is more difficult to inspect every part of the attic conversion out after it is finished and hidden under flooring and plasterboard.
- An attic conversion will usually require a new floor to be constructed above the existing attic floor joists. This is because an attic floor is not designed to support normal floor loadings, it is only designed to support the loads associated with occasional access. A gap should be left between the new floor and the old floor to avoid load being transferred between them. Therefore the new floor will either hang above the old attic floor or more likely, as head height is usually limited, the new floor joists will hang between the old attic rafters.
- The new hanging floor referred to in 3 above will require support at both ends and this is usually done by installing steel beams either side of the new floor. The steel beams can then be used to support struts which prop the roof rafters, this allows the existing internal timber truss members to be removed. The steel beam should be paint protected against rust and then fire proofed. The engineer’s drawings and specification will cover these specifications.
- The most difficult problem for the engineer is how to support the steel beams. Depending on the wall construction this can be difficult.
If my experience is anything to go by, there are a large number of attic conversions that do not meet the building regulations and are dangerous. The owners are probably unaware as the internal walls below the attic are accidently supporting the attic above. But as these walls are not designed for the additional load any changes to these walls during renovations, or fire, could cause a sudden collapse.