Things you need to know
One of the most difficult cuts to make with a Petrol Saw is the ‘vertical cut’ needed for cutting a vertical DPC or opening up a cavity when building on an extension to an existing building. The same applies for cutting new doors and windows into an existing wall. The task is made more difficult knowing that controlling dust will need water suppression to comply with the HSE and legal requirements, as will wearing suitable PPE.
Wall Cutting Guide
Using a Wall Cutting Guide which fits simply to the wall and is fixed with two expanding rubber bolts will give you an easy edge to follow over a distance of up to 210cm. It will make cutting a vertical DPC or opening up a cavity up to 4” or 10cm simple and very accurate.
The thing to always consider with the safety of the saw is never to over-reach the height for cutting. Never bring the running blade above shoulder height and never use a ladder. The thing with the Wall Cutting Guide is that because the Guide can be easily re-positioned with the existing holes or a new pair of holes, there is no pressure to over-reach. Simply wait for the scaffold lift to be moved up, or the installation of a suitable scaffold tower. Then reconnect the Guide, align the cuts and continue the cut(s) to the next lift.
Removing the Wall Cutting Guide after the initial cuts have been made, will allow the saw to be re-introduced to the cut slot and for the cut into the cavity to be completed. Use a 14” machine to cut through brickwork or render to ensure the cut goes through into the cavity.
When cutting out a new door or window into an existing wall, remember that you CANNOT use a petrol saw indoors (even if it is well ventilated) as the machines give off carbon monoxide. Use a 12” or a 14” electric machine and plan the cut around the need for controlling dust.
Always consult a specialist or a Structural Engineer when breaking into existing walls and note that the Wall Cutting Guide is not a structural support of any kind.