Wood shingles can benefit from a pressure wash as the grit that accumulates can be totally removed. The grit can cause damage as the wood moves with the wind and the changes of temperature. The jet of a pressure washer can actually damage wood shingles, especially if they have dried out.
Before spray cleaning your wood shingles you should ensure that you will be able to work through without having to stop to move things. Remove all furniture and plants against the shingles that can be removed. Anything that could be damaged by getting wet from the spray should be moved or covered. Turn off the mains supplies to any outside lights in the area that you will be spraying. If you are aware of any cracked or damaged shingles you should make a careful note not to spray wash them. Carefully close all windows and doors. If there is someone in the house they should be aware of you spraying and check before trying to leave the house.
Wood shingles are not made of a strong material so you should not use a very high pressure to clean them. You should also be aware that wood can be damaged if subjected to a constant spray so keep the spray moving. Use a tip for the sprayer that will fan the spray out over a wider area rather than provide a single strong jet. In some cases shingles can benefit from a spray wash if they have been allowed to dry out.
Starting to Spray
You should always start spraying from the top so that there is no risk of you covering areas you have cleaned with the dirty water from areas above. Spray with a downward angle on the spray head so you don’t force water up into the joints between shingles. Introduce the spray to the shingles rather than simply turning on the spray with the spray head pointing directly at the shingle. Spray with a smooth side to side motion and try to cover a single shingle at a time. This will stop lines being made by the sprayer across a shingle that has been partially sprayed. Spray from no closer than a foot unless you have turned down the pressure.
Shingles can shatter quite easily so don’t use excessive pressure and keep the spray moving. Although not mandatory it is always a good idea to wear protective goggles while spraying. Spray bounce can be very unpredictable.
Although washing shingles with a spray washer is usually enough you should be prepared to go over some shingles with a scraper or sand paper. Wait until the shingles are thoroughly dry then look for any that did not clean up as well as you expected. Clean these separately to give that finishing touch.
Once you have the shingles cleaned it will be a few years before you have to do them again. Don’t forget, though, that spraying shingles can be a form of maintenance if they are drying out.