Painting old wood siding?
arkitkt
| Posted in General Questions on
I’m looking to remove the vinyl siding from my house and either paint the old wood clapboard siding or remove it and replace with it LP, Hardie, or cedar – or maybe Boral polyash. Still doing the research on which siding to use. I’ve removed a small section of vinyl and the old siding is in pretty good shape but I’ve been told I’ll regret leaving the old wood because paint will never stick to it. Blown in cellulose has been installed directly behind the clapboards and I’ve heard that also reduces the life of the paint. Thoughts?
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Replies
Michael,
Before making a decision, you should determine whether your old siding is contaminated with lead paint. For more information on this issue, see:
Managing Lead Paint Hazards
Lead Paint and Old Clapboards
I've seen issues on houses that had wall cavities filled with blown in insulation (after decades of no insulation). The paint starts to blister and peel. May not happen on all houses, but I've seen quite a few that had paint issues.
Michael,
If your house has no sheathing, and the cellulose was installed directly against the back side of the clapboard siding, the wall assembly details aren't ideal. Your wall is missing several important components, including wall sheathing, an exterior air barrier, a water-resistive barrier (WRB), and a rainscreen gap.
What to do about it depends on your goals and budget.
Thanks for the comments - if we take the old siding off my plan was to go back with a better system. I'm considering spray foaming the walls from the exterior, either Zip or Zip R 1" sheathing for the WRB/air barrier and a rain screen before the new siding is installed. I know the current wall details are not ideal and we would like to have a better insulated house, we're just trying to decide if removing the old siding is worth the expense and mess - or if the existing wood could be painted and last a few years without the paint failing. We're in climate zone 4 - mixed-humid.
Replacing the cellulose with foam isn't really going to be "worth it". In most cases you would be able to pull the clapboards and most or all of the cellulose would still be standing, which would allow you to install the ZIP sheathing without re-insulating. The whole thing. If in a few places the cellulose falls out, carefully cutting out and fitting in high density rock wool or fiberglass should work just fine.
If the cellulose was dense-packed it would SURELY not fall out, but I've personally seen ~30-year old cellulose insulation installed at lower density (with 2-hole method) that stayed perfectly in place during a full-gut rehab of a plaster & lath interior. YMMV.
Simply pulling the vinyl siding and painting the clapboards won't work. Direct wetting of the clapboards from rain would result in wetting of the cellulose- more than just the paint will fail. The vinyl siding has been what kept the old clapboards from failing, the old paint behaving as the WRB, and the space behind the vinyl being the capillary break from regularly wicking moisture.
The existing cellulose was not dense packed, and we've opened up a few spots over the years from the inside with some other renovation work and from what I've seen, I think most of the cellulose will be on the ground if/when the old siding comes off. So I'm planning to re-insulate the entire house with something, either foam or new cellulose, if we go that route. And personally I've not been impressed with cellulose. But maybe that's because we have the 2-hole stuff and some thermal imaging I've done shows lots of gaps in the insulation.
Dana, I do have one question regarding the wetting of the cellulose you mentioned. I do agree the vinyl has protected wood for the past few decades, but do you think the inside of the walls would get that wet if vertical joints of the clapboards, the corners, around windows, etc. were caulked. I've seen houses in the area with this set-up, blown-in directly behind the clapboards - and while I've seen the paint curl, I'm not sure I've heard about any structural issues. But, then again maybe they're there and the owners just don't know it yet?
Clapboards will always leak eventually, so dense packing against them won't be as resilient. While the cellulose will redistribute that moisture and offer some protection, it'll also store up any bulk water leakage, risking localized rot and rusting nails when you go that route.
With the vinyl siding deflecting most of the bulk water and allowing the exterior of the clapboards to dry quickly it's fairly well protected. Even the tiniest crack will wick surface moisture (even dew) in to the clapboards.
For less money than stripping the siding and re-insulating you could leave the clapboards in place as the de-facto sheathing, dense-pack over the existing cellulose, and add rigid foam or rigid rock wool over the exterior.
I've researched adding rigid over the exterior of the clapboards but I'm concerned about the detailing, particularly around the windows. With the air leakage into the house with the old clapboards in place, do you think we would also have increased risk of condensation in wall in addition to the wicking of surface water?
Just asking because since the old clapboards are in such good shape, it's hard for me to come to terms with ripping them off and replacing them. We definitely want a better insulated house and I'm leaning towards removal, new insulation and new siding.
Michael,
Q. "With the air leakage into the house with the old clapboards in place, do you think we would also have increased risk of condensation in wall in addition to the wicking of surface water?"
A. Your question is confusing. Under what circumstances are you worried about increased risk of condensation? Adding exterior rigid foam will reduce rather than increase the risk of condensation.
Sorry for the confusion. I don't plan to add rigid to the exterior - I'm either leaving the wood clapboards and painting them, or taking them off, insulating, using Zip and a rainscreen. If I leave the wood clapboards with the blown in cellulose behind, will there be a risk of condensation in the walls due to air leakage through gaps in the clapboards? Is this a risk in addition to the wicking Dana mentioned?
I'm still researching the best solution for our house so I'm visiting this topic with one more question. I'm concerned what the vinyl siding on our house is hiding so I definitely want to remove it and inspect. But I'm not sure we can afford to remove the old wood, re-insulate, re-side, etc. right now. But when we remove the vinyl I thought about taking off a few clapboards at the bottom to inspect for water damage at the sill. I've read some articles that no insulation in old house walls is better that blown-in cellulose (the loose two hole kind) because of moisture being trapped in the walls, etc. I've also read the it can increase the humidity in the house causing further issues with condensation on windows (which we have - original 1920 windows with exterior storms) and increased potential for moisture in the walls from the higher humidity.
So, would we be better off removing the insulation if we're going to remove a few boards to inspect anyway?
By caulking around the windows, corners, etc. (but not the horizontal clapboards) I'm hoping to reduce air infiltration anyway once the vinyl is removed.
Michael,
Q. "Would we be better off removing the insulation if we're going to remove a few boards to inspect anyway?"
A. No. If you are talking about cellulose insulation between your studs, you definitely don't want to remove it. Removing insulation will increase the air leakage rate and increase your energy bills.
If you discover any moisture or rot issues, describe what you find, and (if possible) share photos so we can provide advice.
Michael,
Are you going to do the work? You can be sure there is lead on that old siding. This is a big expensive job you are planning. Do not do any work, just to get by. Think about the details. New siding will impact all your windows. Is there space to add to the siding without affecting the look of the eave, etc. In the long run, take the siding off and insulate is going to be the best approach. Messy but best. Maintain a balance between Ideal and good enough. Maybe what you need to do is put up new vinyl.
Thanks for the comments Jonathan. Definitely not trying to just get by. We just really like original wood siding - our house still has the original windows we're rebuilding, etc. so we just like to keep things original when we can. I've removed a little vinyl and the wood is in excellent shape from what I've seen so far. No paint even peeling so no lead to scrape. I've worked out the details with the windows and eaves. I'm looking at over-roofing with rigid insulation so the eaves will be rebuilt anyway.
I definitely understand that removing the old siding, insulating, etc. is the best long term approach. I'm just trying to figure out if leaving the wood siding with cellulose behind it (if it's all n really good shape) is just a dumb idea.
Michael,
Is this your forever house? I have been working on my 1830 homes for the past 30 years. At age 40, real wood was the way to go, now at 70, the new Boral looks really good. You might investigate installing new siding over the old. The old siding becomes the sheathing. Hardie says you can do that, if ...., or wood shingles, or... A lot depends upon your style.
Following up on an old post - one more question: I understand there may be issues with the cellulose being in direct contact with the wood clapboards. That is if we remove the vinyl and paint the existing wood. We have a few areas of the house where spray foam was applied directly to the back side of the wood siding. would this be an issue if the existing wood was painted?
Thanks again, just trying to determine if removing the vinyl and painting the existing wood would buy us a few years until we remove the wood and re-insulate, add sheating, etc.. We're needing to replace a few rotted sills and I'd like to go ahead and remove the vinyl to determine the condition of the house but we don't want to cause damage to structure if the wood siding stays.
Hi Michael,
I think your question was answered a few times in this thread. Insulation installed directly to the back of wood siding is a risky assembly. Right now, the vinyl siding is beneficial. You are better off leaving the vinyl until you are ready to do your complete insulation, sheathing, WRB, and siding upgrade.
>"I think your question was answered a few times in this thread. Insulation installed directly to the back of wood siding is a risky assembly."
That said, with a Class-II or tighter interior side vapor retarder and good roof overhangs and good bulk-water management it might make it. Robert Riversong has built perhaps dozens of NEW high-R houses in DOE climate zone 6 VT with nothing between the ship-lap siding and interior finish wall but dense packed cellulose, sometimes using vapor barrier latex as the interior side vapor retarder.
While he denies that it's by design, the roof overhangs on his houses tend to be a foot or more per story, which is a LOT more forgiving with much less bulk-water risk than a near-zero overhang Cape.
I understand the possible risks but I'm also concerned about what the vinyl is hiding since we have a few rotted sills. The other issue is we really like the character of the old wood siding and really don't want to replace everything with new - and from a little vinyl I've removed it's in excellent shape. Of course we don't want rotted studs either.
The reason I revisited the question is that I've talked to a couple contractors and a historic preservation person and all said they've seen this install (insulation against the siding) in the past with no issues. One even said he caulked the bottom side of the clapboards to insure no water could get into the walls. Not sure that's the correct approach but apparently is has worked so far. I know I've seen paint fail but I'm not aware of structural issues behind the siding.
But it sounds like the best options are we're either stuck with vinyl or spend the money to remove the vinyl and wood and start over. No easy answers I guess.
I understand Michael. And perhaps it is worth removing the vinyl for the sake of inspecting the current condition of the house, particularly if you already know that there is some rot, and if it will not be long before you do your upgrades. I know there are lots of old houses with no sheathing in which the walls have been retrofit with cellulose. And they're not all rotting away. I tend to be cautious and since that is not best practice, I don't recommend it. A lot of these situations don't have an ideal answer and in the end are a judgement call.