Completely paint with wood filler?

Question

I have a very old house with many layers of exterior paint. I am trying to have a new paint job "done right". They removed as much paint as they could using stripper and scraping, but there was still a lot left.

The paint is embedded deeply into the wood grain.

The painters applied a layer of wood filler over the entire side of the house that's being worked on, and then sanded it smooth. Is that appropriate? Will there be problems from using that much filler? I haven't found any discussions on Google that this is a valid technique for dealing with paint that won't come off.

Does this seem reasonable?

Additional info: The house is 70 years old, the part of the house I'm talking about is the original siding as far as I know, and it's redwood lapboard.

Answer 1

You say it's an old house. I suppose that if the siding was practically at the end of it's rope, plastering it with wood filler might extend its life a few years. I helped replace the siding on an old barn once that was practically plastered with putty. I don't know how long that treatment lasted; I only saw the final/end result (zillions of chunks of putty were falling out as the siding was being replaced).

So, I think it's safe to say that wood filler will eventually chip/come off, especially if it was applied over stripper soaked paint. Wood often contracts and expands to a greater degree than wood filler and old wood often erodes, which leads to putty failure. Putty shrinkage might have had something to do with the old barn, but that's something else to be aware of.

Under ideal/indoor conditions putty lasts for a very long time (decades, maybe), but in this case, it's exposed to the outdoor elements. So, I would hope the wood filler lasts for 7 years but I wouldn't expect it to last more than 14 years (it totally depends on too many untold variable). I don't think that this is an immediate problem; you should be okay for a while. But when the time comes, be prepared to replace the siding.

Also, the type of wood makes a difference. Oak, which is hard, will hold the putty better than pine or cedar which is soft. Oak trim is still very common... whereas really old houses might have been built entirely from oak.

It's possible that the contractors are just being lazy or hasty. Yeah, they had to sand it either way- either sand wood filler or sand wood- and sanding wood filler is a little easier. Plastering it all over siding is not usual. However, there may be a justifiable reason, like the siding was beyond saving/sanding, or there were so many cracks, all the way through the wood, that simply can't be sanded (in which case I would ask, why not replace the siding now).

Always ask the contractor for references.

Answer 2

I use a heat gun rather than chemical strippers. It's easier and usually all old paint can be scraped off. Heat guns do have their own set of special considerations and safety precautions but overall it is a better way IMO.

That being said, even if you remove all the old paint it is common to be left with a surface far from perfect. I use exterior grade spackle to skim coat outdoor trim prior to priming and painting. It dries quicker and is much easier to sand smooth than wood filler. The surface needs to be clean, and it sticks better when the wood is damp.

Wood filler is probably OK if it was applied correctly and sanded properly after application. Way too much work and $$ for me to use it, except for areas where a hard sub-surface is important like handrails, doors, window sashes; areas likely to be touched.