Causes of Sill Damage
by Ronald W. Gower of Craftsman Home Inspection
Termites often enter wood sill areas in a home at masonry exterior steps/slabs. Termites will eat wood members often causing structural failure and expensive repair costs. An inexperienced home inspector will sometimes miss termite evidence/damage. This can lead to unexpected bills after a closing. Make sure your home inspector is experienced in termite pest control. The best inspector is a person that is actually working in the termite business. If the inspector is also completing a building inspection he/she should not violate ASHI standards in accepting any pest control work as a result of a paid termite inspection coupled with a building inspection. The buyer needs to be assured that the home inspector is not completing work with a built in conflict of interest. Avoid any conflict of interest.
I have been in the termite control business for 27 years. I have treated many concrete/masonry steps and slabs to control termites. A step or a slab is very much like a pile of dirt in contact with your home. This pile of dirt will create an avenue where termites can sneak into a home and start munching on wood members. I have seen a lot of structural damage caused by termites. A tell tale sign is to look for compression of a sill member. A wood sill member is attached to the foundation. If the sill has weight on it the sill will compress like a wet sponge. The settlement is caused by the termites eating the interior of the wood and leaving holes and gaps that can collapse the sill to the consistency of cardboard. Steps and slabs are installed after the main foundation is poured and the grade backfilled. This leaves a gap just big enough for termites to enter the house between the steps and slabs. Termites are smart. They would rather sneak into your house than just build a termite tunnel up the side of the foundation. They can build an exterior tunnel but they have been to school. Termites are actually building engineers. They make their own concrete which is the tunneling material. So for example an inspector must be very careful in any sill areas in the basement adjacent to exterior steps and slabs. Porches built on slabs are common entry points of termites.
Wood rot in sills adjacent to steps and slabs is very common also. Builders will often omit metal flashing on the sill/wall/sheathing surface before the steps or slabs are poured. Some material such are “Ice and Water Shield” can sometimes be used. Years ago asphalt paper was allowed but the paper can quickly deteriorate exposing sills to water. Rotting sills is often the result after years of water leakage into wood members. In many cases it is impossible to determine if there is proper flashing. I will often look under the siding with my mirror to determine if there is some evidence of flashing. Water stains and rot can often be visible in the basement at sill areas adjacent to steps and slabs. There is no way to tell the extent of rot damage unless the step/slab or portions are removed. An inspector must look very carefully at these areas.
When damage is discovered you should get three estimates for repair and negotiate before a closing or be prepared to absorb the costs yourself.