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ednelson100

Roof Sag-fix it or leave it alone?

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Hello all,

On my 1991 Itasca I discovered some small pin holes corroding through the aluminum sheet roof by the rear vent. I have decided to fix that area and re-coat the entire roof with Henry 887 Tropi-Cool 100% Silicone White Roof Coating.

  The roof also sags from the weight of the AC unit and the lowest spot is an inch and a quarter sag in front of the AC. The sag is currently not causing an issue other than a pool of water accumulating whenever it is sitting level. In my driveway it is at an incline so only when traveling it pools up.

  I have read the posts on how to fix this by removing the AC unit and constructing an aluminum box tubing frame across the top to pull the roof up. I could do this myself but not sure if I should mess with it or just leave it alone. I would appreciate anyone that may have an opinion on this.

Thanks,

Ed

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Look carefully at where the sag is and where your countertops and dinette are. I jacked my roof from the inside and cut 2 stair rail banisters to fit.  One on the corner of the countertop and one on the dinette seat back. No more sag or leaks.

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Thanks WME,

   That would sure be a simple fix but you have a different Toy model than mine so I do not believe posts in the coach would be feasible. My roof sag is all in the center in front and rear of the AC. I wonder if anyone has tried something like your fix on an ITASCA model?

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If the simple inside post thing won't work then could you do a combo of post and cross beams inside? They may not end up at 90 deg angles to the inside but from where ever the post could be "hidden". The other choices require a double cross beam setup.

A full width 1.5"-2" angle iron beam (u channel or sq tube will work too). Lay it down and drill through the roof, use a 2" piece of  1/8" strap iron on the inside to spread the load. Bolts every 8" or so. One crafty member did some beautiful steam bent laminated wood inside cross beams. Another cut the inside beam from solid wood with a curve in it.

The outside beam needs to be blocked up at each end about 1/2". As you tighten the through bolts you can adjust the amount of torque on the bolts and give the roof a very slight positive curve to prevent water pooling on a flat roof.

Do this in front and back of the AC.

I use the term angle iron as a generic term steel or aluminum will work, but aluminum is a bit bendier. Of course,  the bare metal must be painted.

As always all this depends on your skills or pocketbook. A 1.5" sag is a lot and it's only going to get worse over time and cause increasing roof damage.

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Inside bracing is the best option.

The pinholes might be from galvanic corrosion.  How is the roof built? Is there steel involved?  Two different metals (aluminum and steel) will cause galvanic corrosion when moisture is present and give you the pin holes.  Check the HILO Forum for similar issues.  Even if not, the pin holes are from moisture under the aluminum roof. You have issues.  

Simply use the Eternabond tape over each hole.  Issues are that most of the holes are not visible from the outside, only from inside when the light shines through, but you'd need to remove the ceiling to see this.  If you have holes then yo have water, so ceiling probably needs to come out.  Start digging it out until you find no more wet, then dig a little more.  so, for a one foot circle of wet you would maybe dig out a 1.5 foot circle.  Lucky if it is that small.

Then cover all with the rubber roof coating.  re-add the rubber roof coating every 2 years, or touch up the problem areas more often.

Lap sealant every year on seams.

 

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39 minutes ago, allsummer said:

"Inside bracing is the best option.

The pinholes might be from galvanic corrosion.  How is the roof built? "

Thanks for your help,

     Yes, I am trying to figure out how to make an inside bracing like WME suggested. The roof is wood, styrofoam, and aluminum. The aluminum corrosion was caused by one leak from the vent and then later another leak when the black water tank air vent cap blew off and rain got in. I have already cut that section out to completely let dry, repaired, and coated it with  roof coating.

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Been putting my roof sag off and it is getting worse as WME predicted. I am about to start on a fix now.

WME,

Could you possibly post a picture of your inside banister fix?

Thanks

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My floor lay out was different, but effectively I used the equivalent of a banister pole at the sink and one at step well dinette corner.

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Stripper pole, that's funny.

I'm going to get some pole jacks from home depot and experiment with them.

Thanks for your help.

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