CLEANING

Can moss buildup cause my roof to leak?
Heavy moss can cause water to back up the roof enough to run over the top of the shingles. The buildup should be removed. Moss retains soil and moisture that could harm the wood over time.

My cedar shake roof is surrounded by tall fir trees and the needles accumulate in the spaces between the shakes. Should I have these cleaned out periodically?
Yes, it is a good idea to have a professional clean the debris off your roof. Cedar needs to breathe, and therefore any accumulation of needles, branches, leaves and dirt will affect its lifespan.

What can I do to prevent moss buildup on my cedar roof?
Zinc or copper strips nailed at the ridge cap can be used to control moss for a limited number of courses. Reaction between rain and the zinc or copper forms a mild solution that is carried down sections of the roof for two or three feet. The optional use of these strips can be eliminated if you are using Certi-Last® products. Complete care and maintenance recommendations are available in the CSSB's Care & Maintenance Brochure.

What will zinc or copper napthanate do to my roof?
A zinc or copper napthanate, in solution form, works to preserve your cedar roof and to retard future surface growth. Consult your local professional, competent contractor in your area.

Do I need a license to power wash and treat roofs?
You should check with your State's Contractor's Licensing Board to find out if what you are doing requires a license.

Can you recommend a good cedar roof preservative?
The CSSB does not recommend brand names. The CSSB does, however, recommend if using a topical treatment that it offers a MSDS (Material Safety Data Sheet that lists product ingredients and safety precautions), is labeled as a cedar roof treatment product, is a water repellent, UV inhibitor, and/or EPA registered wood preservative, and has a manufacturer's performance guarantee. Do not use a topical treatment that: makes outrageous claims (such as a 10 year effectiveness), makes fire-retardant claims, is a sealant, waterproofer or plasticizer, or contains unfortified linseed oil, diesel fuel or crank case oil.

Do I need to powerwash my cedar roof?
Powerwashing, done correctly, is one of the options available in the care and maintenance process. When done incorrectly, however, powerwashing can seriously damage a cedar roof. Check the CSSB's Care & Maintenance Brochure for care and maintenance guidelines.

Should I seal my cedar roof to keep out moisture?
No. Never seal your cedar roof. Sealing the roof will lock in moisture that would otherwise naturally evaporate during normal weather conditions. Cedar needs to breathe and thus a water repellant type product, rather than a water proofer is the best route to follow. See the CSSB's Care & Maintenance Brochure for complete topical treatment product guidelines available from the CSSB.

Can I use paraffin oil on my roof?
Yes, if it is a component of a proper cedar roof maintenance product. Check the CSSB's Care & Maintenance Brochure for guidelines. Paraffin is sometimes used as a carrier for active ingredients and will usually weather away within six months.

GENERAL

Are oil based products any good for the roof?
There are a variety of options available for topical treatments. Refer to the CSSB's Care and Maintenance Brochure for the full guidelines available from this organization. Keep in mind that the CSSB does not recommend brand names of products.

I have a cedar roof on my home and it was recommended I have the shakes oiled. Is this a good idea?
In humid areas oiling shakes does not allow them to breathe and they cannot dry out properly which could shorten their life span. The CSSB recommends you try a good fungicide/preservative. Keep in mind that no by-products, such as motor oil, should be used on cedar roofs. Hot, dry climates tend to accept oils better than moist/humid climates, simply due to the fact that oils can seal unwanted moisture into the roof. Please see the CSSB's Care & Maintenance Brochure.

REPAIR

Is it OK to nail down portions of shakes which have curled or bowed for them to lie flat again?
The CSSB recommends replacing the shakes if they are curled very badly.

We are having problems with our shakes cracking and falling off. What do we do?
This could be caused by the nails or the nailing technique used at installation. Contact your local Approved Installer for assistance.

Should my contractor be walking on my roof using cleated boots/shoes? Will the tiny holes compromise the longevity of our shakes?
Small indentations made by cleats usually rebound over time.

My roof was leaking and a relatively inexperienced contractor came out and sealed up large areas with a few tubes of caulk. Is this normal?
No. Caulk is used to seal small areas, not substitute for proper repairs. Caulk will not stick to unfinished wood; it is only a temporary fix for cedar. Caulking is used successfully on finished wood and on metal flashing. Contact an Approved Installer for more help.

Is it ok to walk on my shake roof to examine it as it ages?
The CSSB does not advise homeowners to walk on their roofs themselves; if a roof survey is needed, ensure that you hire a professional contractor to do this work for you as s/he has the proper safety equipment, training, and procedures to perform this work safely.

We have preservative treated shakes on our 10 year old roof and some of them are starting to split. Is there anything we can spray on them to help them last longer?
Some splitting of the shakes over time is normal. If the roof is not leaking then the splits are not doing any damage and should be left alone. A professional can insert metal shims under any wide splits if you consider it to be necessary.

What can I do to prevent the shakes on my roof from turning gray?
There are many topical treatments available that contain color tints. Contact a local, competent, professional paint contractor/paint store for more details. If you have a pressure-impregnated treated product, always check with the treatment company to obtain their recommendation on roof maintenance prior to authorizing your contractor to begin work.

How do you repair a very small section of a cedar roof?
See the repair diagram in the CSSB's Care & Maintenance brochure.

FINISHING QUESTIONS: PAINTS, STAINS & COATINGS

How can I remove paint from cedar shakes without damage?
The CSSB would suggest speaking to a local painting specialist regarding this matter. Each project has its own unique characteristics and challenges, so caution and expert advice is necessary.

What paint/stain/coating/finish should I use on my roof/sidewall?
For specific questions on paints, stains and coatings the CSSB recommends contacting your local, Approved Installer or local, competent, professional paint contractor or paint store. The CSSB does offer some information on this topic, in its Finishes/Coatings brochure (1.5MB PDF).

Is staining a problem for painted shingles applied with electro galvanized nails?
The electro galvanized nails can get moisture through the shingle. Not only might they rust, but the paint on the nail head will come off and the rust will bleed through any cracks in the paint.

For further information on finishing please go to the finishing page.


Warning/Disclaimer
As with all construction projects, ensure that your local Building Official approves of the installation method used in your local area. The CSSB assumes no liability whasoever for any application nonconformance.