Existing structure may dictate best siding options

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This article was published 23/06/2018 (2638 days ago), so information in it may no longer be current.

Question: We have a 1940s cottage that is sided with tongue and groove pine with many different coats of paint on it, from over the years. It is also not in the best of shape with some cracking, warping, etc. We painted it, but the paint peels off and bubbles, so we want to eventually cover it up.

The inside of the cottage was all spray-foamed, so removing the siding is not an option and we have installed all new windows. I don’t really want to put vinyl siding on since it takes away from the character of the cottage, and in my opinion looks cheap. The cottage is just three-season; it is not used in the winter.

Can I put something like four-by-eight sheets of outdoor SmartSide siding directly over top of the painted pine, or do I need to strap it? I would prefer to put it right on top, maybe with a Tyvek layer only, but I didn’t want a moisture problem eventually rotting away the pine behind the new siding.

Can I do this, or do you have any other recommendations to cover it up without using vinyl, but without breaking the bank?  –Dave Twining

Answer: Covering older siding with new material not only improves the cosmetic appearance, but may significantly prevent future moisture intrusion and damage, very likely with the older siding. The key to the success of your upgrade is to ensure the condition of the substrate is good enough to support the new siding, or other modifications may be required.

I see a couple of concerns with your proposed addition of new siding over top of the older, deteriorated wood siding. The first issue is the previous installation of blown-in foam inside the siding. That material will not only provide good insulation and air sealing, it should adhere very well to the siding. That would make removal of any damaged wood difficult, without tearing out large chunks of the foam insulation.

Unfortunately, you should endeavour to remove any badly rotted siding before beginning any upgrades. If properly done, the new siding should prevent moisture damage to solid areas of the existing wood siding, but will not stop further rotting of already-affected areas.  If you have only small areas where a probe can easily penetrate the old siding, they may still be able to be removed by carefully cutting or chiselling.

One problem with leaving the old siding is the possibility of the rot spreading to other, undamaged areas, but mainly with integrity of the substrate for the new siding. If this is rotten, it will not properly hold fasteners for any new siding you choose. That may cause looseness and damage to the new siding over time, and could partially ruin an otherwise good upgrade. So, if you have more than a few small areas of badly rotted siding, a complete strapping job may be required to ensure proper adherence of any new material.

If the older siding is not soft or overly damaged, you may be able to install new siding without the use of wood strapping. You will still require either building paper or housewrap installed first, to protect the wall cavity from moisture and wind intrusion.

While most sidings appear to be complete protection from exterior moisture and elements, they can still allow some rain and wind penetration. The thin membrane layer behind will be critical in stopping this from getting into the old siding and wall behind, ensuring adequate protection for years to come. This could be stapled directly onto the old siding, as long as the surface is good enough.

The next issue that may affect your decision is the thickness of any new materials added to the exterior walls. If your new windows and doors have full-thickness brick moulding, which protrudes out from the siding more than three or four centimetres, you may be all right depending on the condition of the old wood.

If not, you may have to install additional brick mouldings, or build out your window frames to accommodate the thickness of the new siding. I’m not sure of the thickness of your proposed siding sheets, but it is likely thin enough for this not to be much of an issue, even if you have to strap the walls. If you choose a better-quality siding, like cement siding or various masonry options, it is more likely you will have to build out your window and door frames to allow proper installation.

I, personally, am a fan of vinyl siding, as it is a very cost-effective, long-lasting and easy to install product, but understand your esthetic concerns. You may still want to look at it as one of your options, because newer styles may surprise you at their excellent appearance.

Choosing whether to install complete wooden strapping over your older cottage wood siding is mostly dependent on whether it can support the fasteners from any new coverings you install. Looking at the brick mouldings on your windows and doors, ensuring enough thickness for allowance of the new material may also dictate which way you go with your upgraded siding.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba (cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.

trainedeye@iname.com