Do It Yourself: Rotted window sills should be replaced

Q: My house has a lot of wood-framed windows. The windows are in good condition, but several of the sills have rotted areas. I know it is best to replace those sills, but I can’t afford it right now. Can I repair the sills instead?

A: It would definitely be best to replace the rotted sills; replacement is always the best option for rotted wood. But if the rotted areas are not too extensive, they can be repaired.

Ordinary wood fillers won’t hold up long in exposed outdoor conditions, so the best bet is to use one of the special products designed for rotted-wood repair.

One of these, Minwax High Performance Wood Filler, is available at many home centers and hardware stores. This is a two-part filler that is mixed immediately before use.

Start by cleaning out all the rotted wood to create a cavity of sound wood that will not continue rotting after the repair is made. If some weak wood can’t be removed, use Minwax High Performance Wood Hardener to harden the fibers; this is usually applied with a brush.

When the cavity is ready, follow directions on the container to mix some of the wood filler. If the cavity is deep, it is best to fill it in several layers, letting each set up before the next is applied.

Smooth the final patch as carefully as possible; when it hardens, it can be chiseled, sanded or otherwise shaped with regular woodworking tools. The finished patch can then be primed and painted.

A caution: These wood fillers have a very strong odor and should be mixed outdoors. Also, wear gloves and eye protection and observe other precautions on the container.

Another good repair product, used by some pros, is Abatron’s Wood-Epox; visit www.abatron.com and click on Wood Repair & Maintenance for more information.

When you can afford it, you can avoid future wood-rot by having the outside wood on the windows capped or clad with a thin aluminum or vinyl skin. Capping will also greatly reduce maintenance by making it unnecessary to repaint periodically.

Q: My neighbor had a deck built that has no visible fasteners for the decking. It looks great. How is it done and is this a good system?

A: Hidden deck fasteners are increasingly popular and, to the best of my knowledge, work very well.

The hidden fasteners have a couple of advantages over nails and screws besides the smooth appearance: no nail heads or screw heads to corrode and stain, and no nails to pop and cause tripping. A disadvantage is that you will pay more for a deck with hidden fasteners.

A popular type of hidden fastener uses decking that has a groove in each edge. The fastener is shaped roughly like a T. One arm of the T fits into the groove in the edge of the deck board, and the bottom of the T is screwed to the joist under the decking. The groove in the next deck board fits into the other arm of the T and so on.

Pregrooved deck boards are more likely to be found at building-supply outlets and lumber yards than at home centers.