theresa
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from Northern Maine ~ Proud new owner of Lola, a 1960 Shasta Airflyte and Pearl, a 1962 Mobile Scout
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Post by theresa on Oct 17, 2020 7:18:31 GMT -8
I'm very far along in my build, and while doing some work on my trailer yesterday I notice that my roof if sagging. Everything is new... all the roof framing is new, the birch panels are new. What would cause this and how can I fix it this late in the game? The sag seems to be forward of the wardrobe closet up to the shelf above the dinette. So basically the worst possible place... right where the fan is.  2020-10-17_11-14-07 by t_in_maine, on Flickr |
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nccamper
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1962 Forester- 1956 Shasta
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Post by nccamper on Oct 17, 2020 7:56:46 GMT -8
What kind of wood did you use for the framing? Yellow Pine is softer than Popular, oak, etc. I used harder wood near the fan anfd it still saged slightly over the last 5 years.
You could do what Shasta did at the framing near the large front window. Use a piece of metal (iron I believe) running along the framing that makes it rigid/stronger. You can buy it at Home Depot. It is smaller than the 3/4" framing and you need to drill screw holes in it to screw it in place. Wiring may be in the way.
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theresa
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from Northern Maine ~ Proud new owner of Lola, a 1960 Shasta Airflyte and Pearl, a 1962 Mobile Scout
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Post by theresa on Oct 17, 2020 8:10:41 GMT -8
That's exactly what I was thinking of doing; I have a Shasta that used that under the window. There's nothing in the way at all to make it sag and I used poplar. I can use one on either side of the fan framing presumably.
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nccamper
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Post by nccamper on Oct 17, 2020 8:25:41 GMT -8
Either side will work but keep it clear of the edge where the skin may rub against it.
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Post by danrhodes on Oct 17, 2020 11:30:10 GMT -8
I used pine and selected my most bowed boards to give a bit of a crown. Within weeks, it had sagged dramatically. That's on my list of no-nos for a future build... Use poplar or other harder wood and maybe even metal bracing.
My solution isn't great, but I keep a "t-stick" with padding in the camper and force the bow back in the other direction when the camper isn't being used. When removed, the ceiling stays flat for as long as we need it to, then the stick is returned once home.
Since you caught it early, you can add hardwood joists between the existing ones and even sister joists next to the ones you have. I would use interior bracing like the t-stick above to get a positive crown on the roof then glue the new joists down, using heavy weights (I keep 10lb weight plates for this) to force it to match the upward bow shape in the panel.
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Post by vikx on Oct 17, 2020 11:40:44 GMT -8
First of all, the vent needs to be higher than the rest of the rafters. I go 3/4" when everything is new. The shims are tapered from the opening to the rafter height and about 3 to 6" long. This keeps the shim ends from cutting into the roof. <a data-flickr-embed="true" href="https://www.flickr.com/photos/53634851@N03/34866619694/in/photolist-V83xiq" title="Vent Shim 1"><img src="https://live.staticflickr.com/4232/34866619694_f828834e16_w.jpg" width="400" height="300" alt="Vent Shim 1"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script> That way, if your roof sags, the vent area will still drain away from the opening. I think NCs solution will work for your sag. Also, you can add rafters that have been beefed up to help. We used aluminum angle but I think small angle iron will work better. Be sure to pad well between iron and aluminum. I laid Reflectix over the entire roof to prevent rubs or interaction with the metals. |
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John Palmer
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Hi, From a vintage trailer guy located in Santa Ana, CA. It's good to see lots of activity here.
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Post by John Palmer on Oct 17, 2020 12:23:32 GMT -8
I would suggest using a wide Poplar board on each side of the existing rafters. Make certain you look at the natural curve and place the new rafters with the curve facing up. As suggested, use a support inside the trailer, glue and Kreg screw the new rafters.
I'm curious, do you have the closet and the upper kitchen cabinet installed?. The closet and the upper cabinet should hold the ceiling up better, IMO.
John
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theresa
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from Northern Maine ~ Proud new owner of Lola, a 1960 Shasta Airflyte and Pearl, a 1962 Mobile Scout
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Post by theresa on Oct 17, 2020 13:28:42 GMT -8
Thanks everyone for your replies. I selected poplar because I thought it would be sturdier, but even still it sagged. My closet and cabinets are all installed, and it sagged between them. I had already crowned my fan location, but in its current state, the crowning is still lower than the rear sections. I will do a combination of beefed up, sistered rafters, and either a flat piece of iron or angle iron for more rigidity, with a dead man stick inside pushing up while I put it all together.
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Post by wisconsinjoe on Oct 25, 2020 7:25:43 GMT -8
When I re-roofed the Friendship Vacationaire, I was shocked to see saggiing 1x rafters.
I don't know how 1x boards laid flat CAN'T sag. That's one reason I used 2x2s reinforced with aluminum box to stiffen things up on my scratch build. It would not be too late to sister on thicker material, unless you are using original skins.
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sawset
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1958 Mobile Scout
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Post by sawset on Oct 26, 2020 18:19:59 GMT -8
2x2 rails glued to 1/4 ply - I created shelves for storage here 25 years ago that span 4-6ft. Tools etc, floor jacks, other heavy items, they do not sag, at all. Very surprised and pleased they held up. I'm planning on 2x2 for the top rafters here, glued to the 1/8 ply ceiling. My 2cents.
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Post by wisconsinjoe on Oct 26, 2020 18:52:35 GMT -8
If you glued 2x2s to 1/4 ply top and bottom you'd create a stiff torsion box.
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