Skip to main content ↑ ↓
Topic: Hollow Wall? (Read 654 times) previous topic - next topic

Hollow Wall?

It rains tons here in the Pacific North-West ( about 6" in the past week!) and we have a concern about possible water inside the exterior walls.  Our 1993 Grand Villa Unihome (U280) shows only one spot of leakage (coloured roof material near the bathroom Wonder Fan - and since well caulked, along with everything else on the roof,  when I discovered it after a summer rainstorm.  However - when it rains, in addition to the pitter-patter of raindrops on the roof, we can hear what sounds like drops of water landing onto other water - inside the bedroom wall below the window.

What I need to figure out is whether or not this is an auditory illusion caused by water running down the exterior (likely at the rear joint/molding, running from top to bottom vertically) - or is water able to get inside the wall and plop into a pool already sitting inside there?

I can see the 'ghosting' of the internal diagonal framing when looking along the exterior wall from a sharp angle, and assumed that the space between framing was filled with some foam-based insulation - thus filling the space.  From my reading on the Forum, it sounds as if that there is insulation in the space between interior and exterior walls.  Any ideas??
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Hollow Wall?

Reply #1 –
Stethoscope on the wall. If location seems right then drill a 1/8" dia hole about 1-7/8" up from floor. Water comes out or wood is wet, go outside & find where water is getting in. If no moisture then plug hole with small stainless screw or use wood putty, etc.
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: Hollow Wall?

Reply #2 –
 However - when it rains, in addition to the pitter-patter of raindrops on the roof, we can hear what sounds like drops of water landing onto other water - inside the bedroom wall below the window.

What I need to figure out is whether or not this is an auditory illusion caused by water running down the exterior (likely at the rear joint/molding, running from top to bottom vertically) - or is water able to get inside the wall and plop into a pool already sitting inside there? end of quote.

Due to the fact that the void (as you mentioned) is filled with foam I have a doubt that what you hear is a pooling of water in the  walls. I would first check that the window frame caulk is complete and no large gaps can be seen around it and also that the awning top bracket and screws are all sealed and not allowing water in. The next step would be to check the drain line above awning just below the roof radius. In other words any place that would allow water to migrate be looked at. I also would suggest that you do not have coach sitting level, instead have either front or back lower to help with the run off of water. Regarding the bathroom vent leak, I again strongly suggest that a cursory look at the sealant is not sufficient and that you look carefully at every inch of it as depending on the sealer used a lot of them lose their bonding with materials and water can wick under it if allowed.
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Hollow Wall?

Reply #3 –
Quote from: Mike_Sandra_Lloyd –
From my reading on the Forum, it sounds as if that there is insulation in the space between interior and exterior walls.
To the best of my knowledge, your understanding is correct.  In every instance where I've had a look inside a exterior wall, the void between inner and outer "skins" was completely filled with foam.  I don't think it likely that water could actually fall freely through the wall cavity into a puddle at the bottom.

Water leaks, of course, certainly do happen.  The area around windows is one possible point of entry.  Checking as recommended by nitehawk and JohnH might give you some more information.

Where we live, we do not normally experience hard rain.  On a recent trip to Oregon we got a taste of what you might call "normal" weather.  At various times, we also heard some strange noises that sounded like water dripping.  We checked everywhere we could think of, and found zero evidence of water intrusion.  I theorized it might be water dripping off the rolled up window awnings, and landing in water pooled in the exterior window tracks.  Our single-pane windows do not block sound as well as the newer double-pane versions, so I guess it's not totally implausible. 

Any large water leaks in the walls should eventually produce some kind of obvious symptoms, other than a strange drippy noise.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Hollow Wall?

Reply #4 –
Thanks guys.  There is no sign of water on the wooden walls of the bedroom, so I think the issue (if there is a physical problem) it is in the wall.  However I did have a quick look at the trough above the Zip-Dee awning above the bedroom window and all seems in order.  That is a very hefty trough but I will have another look at the sealant.  The weep holes on the lower edge of the window frame all seem to be open and given the size of the awning protrusion above the window, I doubt that the window is the problem.  I will look further though.

With regard to the bathroom fan, I removed it and cleaned the old caulk then bedded it using Sikaflex Self-levelling caulk, then did the exterior of the rim housing another layer of Sikaflex - so no water is getting in there!
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Hollow Wall?

Reply #5 –
On my roof, there was a leaking screw that attaches the shower skylight. The water ran parallel in the roof and leaked down from the power vent. The dark color is from the thin wood layer bonded to the fiberglass. I ended up replacing about 20 sq. ft. of fiberglass. Oh what fun it was. You may want to check EVERY orifice.
1994 U280, Build 4490
Deming, NM.

Re: Hollow Wall?

Reply #6 –
Quote from: Twig –
You may want to check EVERY orifice.

Yup, we stayed under a flock of juniper trees last summer, the pitch was a huge pain to remove. Finally got up on the roof, and whoa! What a mess!  Had the cleaners come over to power wash, and found numerous cracks around the AC and the dome. Some other cracks where prolly caused by falling branches during the monsoons. Had them dry the roof and seal it with the white goop. Not cheap to do ($450.00), but cheaper than a slow leak!  ^.^d
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: Hollow Wall?

Reply #7 –
Three or four years ago we (the DW) could hear water dripping somewhere. checked everywhere I could. Couldn't find any leak spot on the outside. Turned out to be the plastic skylight itself!! When someone made the aluminum frame retainer they Tig welded the corners but did not grind down the weld beads flush with the rest of the welds. The beads broke the corners of the dome and kept the aluminum retainer up "just a bit" and we ended up with water leaking in the inside wall between the shower wall and the other side--the bedroom wall. Guess what? No insulation in THAT wall and so we (the DW) could hear dripping.
Ground the beads flat and added caulk on the corners and no leaks!!
One other leak that WAS apparent was water traveling down from the retainer nuts on top of the rear AC shroud down thru the AC and then dripping on the bed. Smothered the nut recesses and nuts with caulk and no more leaks!!
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: Hollow Wall?

Reply #8 –
Quote
From my reading on the Forum, it sounds as if that there is insulation in the space between interior and exterior walls.

Here's a photo showing the wall.
jor
93 225
95 300
97 270
99 320