The Extension Project – Part 1 (Setting out footings for an extension)

The Extension Project is a brand new series from Skill Builder following the build of a side and rear extension on a semi-detached house. In the first instalment of the series Roger provides an overview of the project and explains the setting out process.

Setting out footings for an extension

“It’s very important when you’re building anything that you set things out properly because if you get it wrong at the setting out stage it has implications throughout the job.

“In other words if you start right; you finish right.

“It doesn’t matter if you spend a day setting out footings for an extension, this is an investment.

“This setting out stage is not the line of the brickwork – that can be done at a later stage using a laser level, this stage of setting out footings for an extension focuses on working out the line of the brickwork – in other words where it is going to be and how far away from the existing building so we can get it in an absolute straight line.

“Start by taking a couple of battons and work out where the extreme edge of the brickwork might be but use something more substantial for the cross piece to avoid rocking because if it rocks even slightly you could throw your brick line off.”

“Take the drawing and work out how far away from the building the line needs to be and stick a screw into the form at this spot. We know that the brickwork is 300mm overall: 100mm for brickwork, 100mm for cavity and another 100mm for brickwork so we can also mark the inside edge of the wall on our cross piece.

“Repeat this step at the other end. Run a line in between the screws at the oiter edge of each forms. Then run the inside line; the lines should then be parallel and the same distance off the building – if they are not it is possible the building is not straight in itself.

“The next thing we do is mix up some mortar, slap it onto the foundation and take our spirit level, line it up and mark it off at the bottom.

“We can then begin to put the corners up on either end of the building and then get the laser level and level through and then run the brickwork between the two corners laying to the line.”

About Georgina Bisby

Georgina Bisby
Georgina Bisby is a journalist and editor with extensive experience covering construction and industrial news and technology, including a particular focus on health and safety, energy and environmental issues.

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