Potential hazards of extensions

May 2012


We have planning permission for a two-storey side-extension and arising from this I would be grateful for some guidance on two issues.

Given the current economic climate and current spatial needs, we are considering doing the ground level first (utility area/toilet/playroom and study) and the first floor extension (two bedrooms and en suite) in four years’ time, could you advise as best you can:

1) if we need to apply for new planning to do the build in two stages — we already have it for the double storey extension?

2) the potential hazards of adding the first floor extension at a later date — best estimate of additional costs, ie extra plastering, removal of roof, potential problems, and is there a particular type of roof we should ask for that will make its removal in a few years time easier and is it an reasonable job for a builder to do (add an extra storey)?


It would be my opinion that you could undertake your extension in a two-stage programme without the need for two separate planning applications as long as you completed the work as per the original application within five years of the grant of the application.

Should you approach the five years from the initial grant and the work is not complete, you could apply for an extension of duration. This could give you an additional five years to complete your development. If you do not wish to complete the first floor you could then apply for planning retention for what has been completed.

The second part of your query is more difficult to answer accurately due to not being fully aware of the design and the structure.

There would be additional costs associated in constructing the project in two stages in comparison to one complete build.

You would have to construct the floor to the first floor section to act as a roof and weather this well enough to prevent water ingress into your newly finished ground floor.

Another potential downside to this method of construction is that over a three- or four-year period you will have builders in twice and have the substantial costs associated with set-up and access requirements.

I would advise employing the services of a local quantity surveyor as they would be able to provide the vital cost information you need in order to make an informed decision on the correct course of action to take

Kevin Hollingsworth is a chartered building surveyor and chairman of the Building Surveying Professional Group of the Society of Chartered Surveyors Ireland