My house is a late 1920’s Colonial in New England. Over the past 2-3 months, I’ve been pulling up the the attic floorboards nailed to the joists in order to then have the existing (settled) insulation topped off with additional cellulose.
I’ve been noticing that several of the second-floor bedroom walls (both interior and exterior) have developed a number of diagonal “hairline” cracks in the paint and plaster beneath. (All the cracking is in walls that were freshly painted over a year ago. No cracking at all can be seen in the first-floor walls.)
Though I can’t be sure when I first started seeing the cracks, it just occurred to me that the loosening of the floorboards above might be causing the walls to rack enough to crack the plaster. Does this seem plausible? Further, what is the proper way to have the walls repaired?
Replies
Seems like a reasonable assumption that pulling up attic floorboards is responsible.
Sprayed cellulose will fill up a wall cavity pretty tightly with two holes drilled in the 8' height, so approach your attic gaps the same way. It may be too late, but drilling 1.5" holes every 4' in each cavity and spraying the stuff in would do the trick. Nonetheless, you may get cracks in the ceiling plaster from all that excitement. But if it's loose fill, it's not that impressive an R-value for the effort if you're just topping up an inch or two.
For repairing the fine cracks, you can try thickening paint with a bit of Polyfilla. That can fill in hairline cracks nicely. If that's not effective, drag over the crack with a can opener or equivalent, and patch with drywall mud.
Geoff
Geoff, many thanks for your reply.
I'm getting a little panicky that perhaps the floorboards served as some important element of the structure of the house. The house has a hip roof. It's not clear to me what now counteracts the downward (and spreading) force of the roof in the direction of the floorboards (perpendicular to the attic joists).
I do plan to reattach the floorboards as soon as I can get the insulation beneath topped off. It may be difficult, though, to get nails (or screws) back in the ends of the floorboards near the top plate (because of the limited working room). It seems evident that the floorboards were originally installed before the roof was put on.
Marc
STOP!!!!!
Before you remove any more floorboards, check out if they are functioning as rafter ties. I had an old house once where there were no rafter ties but the floorboards on the third floor were nailed down parallel with the rafters and served to keep the front and rear walls from being kicked out by the downward/outward forces generated by the roof. You may have the same situation. If so, you can remove a few at a time, insulate, and then replace them before you take any more up. Otherwise, your roof will try to spread your walls apart -- and will likely succeed!
Mike HennessyPittsburgh, PA
a little panicky that perhaps the floorboards served as some important element of the structure of the house
That's a hard call to make. At least with only the information we have now. Snapping some pics and attaching them in can help.
Now, since you say that the cracks are diagonal and fine, I have a suspicion that taking up the attic boards may have reduced how 'stiff' the ceiling was/is. That would mean that you moving about up there might have flexed the ceiling joists just enough to 'ding' the plaster. After all, it only takes a deflection of 1/350 to crack plaster.
Or, there could be some other thing happening. Hard to say, I'm having to imagine a dark attic in somebody else's house, after all <g>.Occupational hazard of my occupation not being around (sorry Bubba)
Thanks all for replying. Attached are numerous photos of the attic floor and rafters. Please let me know if some additional images would be helpful.
Note that as this is a hip-style roof, the rafters extend downward on all four sides - therefore, rafters are both parallel and perpendicular to the floorboards. Note also that the ends of the floorboards attach to the outermost joist, not the top plate, though that joist itself appears to be directly attached to the top plate.
If the ceiling joists deflected during the attic work, wouldn't any damage have been limited to only the interior walls? Hard to imagine deflection at the perimeter of the house.
I just re-read your post, and I'm pretty sure you have the problem I described because 1) your joists are perpendicular to your rafters (that's typical construction for cases I have seen where the floor acts as the rafter ties) and 2) the floorboards were nailed to the top plate before the roof was put on. Even though the floorboards probably don't run full span, they all act together when nailed to the perpendicular joists to resist the walls spreading. If this is true, you MUST tie the floor into the top plate when you re-install, or else install conventional rafter ties. Like, right now.
Mike Hennessy
Pittsburgh, PA