Hugh Cairns: All about wood chip insulation

To improve the comfort of the home pictured above, one solution is to remove the wood chip insulation and re-insulate the entire attic cavity with blown in fibreglass insulation. (Photo: Hugh Cairns)

What should I do if I have wood chip insulation?

Oddly enough, when homeowners think of insulation, they often only think of the importance of it in the winter. Insulation is just as important for your comfort in the summer months because it slows the transfer of summer heat entering the home and reduces demand on your air-conditioning system.

Attics can get really hot during the summer months often reaching temperatures as much as 150°F. On hot days, top floor ceilings act like heat exchangers. With insufficient insulation (and absence of proper ventilation) your attic will get nice and toasty. That heat will, in turn, radiate into your home, countering the cooling efforts of your air conditioning system costing you money.

Hugh Cairns wood chip insulation tip…“Homeowners with wood chip insulation will greatly benefit from its removal and replacement. Replacing your wood chip insulation will make your home feel noticeably more comfortable and energy efficient”.

Considering that attic insulation is relatively inexpensive, there’s little money to lose and lots to be gained from insulating your attic. You will benefit greatly with increased comfort, particularly in the summer months.

If you have wood chip insulation in your attic, it would have been acceptable practise when it was installed. Wood chip insulation is generally considered safe, although it offers very little R-Value for you.


R-Value of wood chip insulation

Back in the day before cellulose and glass fibre insulation products were available, sawdust and wood shavings were commonly used to insulate homes. Before that, most builders and home owners didn’t insulate attics or walls at all, making homes with sawdust insulation better than average.

If you compare the R-Value of sawdust and wood chips to our modern insulation products, the insulation value is poor. Often, the depth of the wood shaving insulation was  insufficient – to today’s standards, and as it settled, it has little or no thermal benefits. If you are heating a home with wood chips in the attic, then you are wasting heat and money.

Wood chip or sawdust insulation – R-1

Blown in fiberglass insulation – R-3

Covering wood chip insulation

Insulation contractors may give the homeowner the choice of covering wood chip insulation with new, efficient insulation products.  My experience is that the home performs better once existing insulation is removed.  Most people won’t remove wood chip insulation purely because of cost. There are a lot of reasons to move towards its removal than to keep it. Therefore, removing it is your best move.

Don’t settle for a contractor that says that it’s ok to leave it. Don’t cut corners. If your contactor doesn’t have the equipment, then look for one that does. In any event, you shouldn’t try to escape removing it. It may cost a few more bucks, but you’ll be satisfied with the results.

Should I remove my attic wood chip insulation?

Removing wood chip insulation

You bet it’s a good idea to remove wood chip insulation and upgrade to a new material. If you have wood chip insulation, it means you’re faced higher energy consumption by its presence and you will experience less comfort. For these reasons, it is a good idea to remove it and replace it with contemporary insulation.

If you have had condensation issues and the insulation has been affected by mould or other health issues, then it is mandatory to remove it. If you are short on attic space for new insulation, then it would be advisable to remove it and replace it with a higher performing product. Some people just aren’t comfortable knowing it’s there and remove it regardless.

Hugh Cairns insulation tip – “Many of us tend to think ahead and consider the impact of our present actions on the future. Adding attic insulation to your home – particularly for an older home that lacks sufficient insulation – can increase the home’s value”.

Removing attic wood chip insulation

Some people may be tempted to leave the wood chips and insulate over the top of them but that can result in future complications.

You can remove wood chip insulation yourself, but I don’t recommend it. Unless you have the right equipment, it is way more trouble than what it is worth. Horsing around with a shop vac in the attic isn’t fun, plus you’ll have to empty it every couple of minutes. Small vacuums are noisy and their exhaust ports can stir up phenomenal amounts of dust.

On top of operating the equipment that you’ll have to Billy Goat your way through the attic, standing on the bottom of the roof trusses, be aware that while you’re hunched over, you’ll have to avoid sharp nails that penetrate the roof sheathing.

Hugh Cairns wood chip insulation removal tip – “The best way to remove attic wood chip insulation is to hire a qualified insulation contractor that has an industrial sized vacuum to remove the wood chips. They are used to navigating attics and are experienced in how to avoid safety hazards”.

After the wood chip insulation is gone, draft proof around all ceiling penetrations. If you are adding recessed ceiling mounted light fixtures, make sure that they are fire-protected, CSA-approved fixtures. Now you’re ready for some new insulation.

Wood chip insulation and knob-and-tube wiring

Removing wood chip or sawdust insulation can be complicated should knob-and-tube wiring be present.  If you find knob-and-tube wiring, be concerned about the validity of your residential insurance policy. A number of insurance companies may not insure your home if it is present. Installing insulation around knob-and-tube often results in a dangerous alteration. For these reasons, the wiring should be disconnected and removed before you reinsulate. If you find knob-and-tube wiring, hire an electrician to inspect and evaluate it.

Attic ventilation and wood chip insulation

The common trait that I see with wood chip insulation and attic ventilation is that they both perform inadequately. There are a host of important benefits of a properly ventilated attic. Adequate attic ventilation reduces cooling bills, extends shingle life, prevents roof rot and ice dams in winter.

My best advice to you is to hire a ventilation contractor to assess and quote your needs. Increasing ventilation is usually not expensive. It’s mostly a few dollars on materials and more on labour. Even if you want to do this work yourself, call in an expert. Increasing ventilation can be a nasty job, done in a dark, cramped, dusty space.