Houseworks: Mulching with fresh sawdust

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Q Can I use fresh hardwood sawdust to mulch my garden? I’ve been cutting firewood and have a lot of sawdust from my chainsaw. It seems a waste to just throw it out. 

A Yes, that chainsaw dust is a valuable resource, and I’ve never had any issues using fresh sawdust or wood chippings on my garden, so I think you’ll be fine. Don’t work the sawdust into the ground, but just spread it on top. That said, if you have any concerns, just leave the pile until spring, then spread it. Mulch doesn’t do much good during fall and winter anyway, so nothing is lost. 

All this said, never use chips or sawdust from walnut trees as garden mulch. It contains a compound called juglone, and this suppresses the growth of plants. This gives walnut trees a competitive advantage, but that’s not what you want in your garden. 

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Finishing an outdoor table 

Q What finish would you recommend for an old granary door from a barn that I’m turning into an outdoor table for my deck? 

A As with most outdoor wood-finishing situations, the finish you choose depends on the look you want and the amount of trouble you’d like to take on to keep it looking fresh. At one end of the spectrum you could just leave the wood bare, perhaps treating it with something like Ecowood Treatment to create an even weathered look that never needs maintenance. That would be the least amount of regular refinishing, but it would also eventually look like the outside of the barn the door came from.  

At the other end of the spectrum there would be outdoor-grade spar varnish. This is clear, so it would preserve the current look of the door but would also require stripping, sanding and recoating about every three years or so, depending on exposure. 

An in-between option would be an exterior-grade finishing oil. This preserves the look you have now but will require yearly re-application. This is easier than refinishing a spar varnish finish because there’s no surface film to strip with oil. The only drawback is that the wood slowly gets darker over the years. 

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Wet walls in winter 

Q Why has the lower half of the walls of my entranceway started to get wet in winter after major renovations, including new windows and weather stripping? This has never happened before, but the paint and plaster peeled badly last winter. I’d like to prevent that this winter. The troublesome part of the wall is solid masonry, while the top half is an insulated wood frame. We installed a heat-recovery ventilator as part of the renovations. 

A Your situation is a classic case of walls that are cold enough in winter to trigger condensation indoors. You’ve decreased the amount of air leakage with the new windows, but this means higher indoor wintertime humidity levels. This airborne humidity is the source of your water. The cold wall surface triggers condensation on the surface of the wall (just like a cold drink in a glass on a hot day), and this didn’t happen before because humidity levels were almost certainly lower. 

You did install a heat recover ventilator (HRV), and this is typically very effective at reducing indoor wintertime humidity below damaging levels. But this is only true if the HRV is operating at sufficient speed and duration to lower humidity sufficiently. It sounds to me like you might not have enough HRV action. 

The other side of this issue is insulation levels. If insulation was increased in the affected area that condensation would stop, even if indoor humidity levels didn’t decline. There’s also a fair amount of heat loss happen through those all-masonry part of the walls. If adding insulation isn’t practical, then lowering humidity levels will work on its own, it will just be necessary to lower humidity more. 

Steve Maxwell has seen wintertime condensation do strange things in Canadian homes. Visit him online at BaileyLineRoad.com for thousands of Made-in-Canada articles and videos on home improvements, renovations and hands-on living.