DIY Pressure Testing for Rain Leaks

[Togger]

I have an impossible to find leak in my travel trailer and I am at my wits end. My trailer is a 40 ft. Park model on a permanent campsite in southern Delaware with a hard room and deck attached so I do not have the option to take it in to a dealer to have a Seal Tech leak check performed.

I am determined to take matters into my own hands and figure out how to do my own pressure test on site. After searching various posts from the past, this is my basic plan.

I am going to purchase a high CFM air moving device, probably a carpet dryer, and rig it up to blow air through the side storage hatch door which is under the bed in the bedroom. I will lift the bed so the air can enter and pressurize the entire camper. To achieve a tight camper I will tape off the sink drains, shower drain, kitchen exhaust, and any roof vents.

Using cardboard and duct tape I will seal the carpet dryer fan into the camper hatch. I will insert a 1/2 inch clear plastic tube through the cardboard so it runs from the inside to the outside. On the outside this tube will be taped to the camper in a U-shape about 1 ft. High to serve as a homemade manometer to detect air pressure. I will pour water into this tube enough to fill the bottom few inches of the tube.

When I start the fan I will know I have achieved positive pressure on the inside of the camper if the water levels become uneven on the two sides of the plastic tube at the bottom of the U. Adequate pressure should range from 1/4 to 1" difference in water height between the two sides.

I don't want to damage the camper with too much pressure so I i will start the fan with a door cracked and then slowly close the door while checking that I don't get over 1" pressure in the manometer.

Once I have achieved pressurization, I will spray all possible leak areas on the outside with a strong solution of dish soap and water in a pump-up sprayer. I expect to see bubbles forming anywhere air is escaping and this is the exact spot water could be entering. I will mark any bubbling areas, repair them, and then re-check afterwards to make sure they are sealed.

I am looking for advice from anyone who has done this type of test. Here are my questions:

1. How much CFM of air will I need to get adequate pressure. I am looking at purchasing a powerful carpet dryer this settings from 2500 to 4200 CFM. I figure if overpowered I can simply reduce pressure by cracking a window or door. If I am underpowered I am setting myself up for failure. Keep in mind this is a 40 ft. Trailer.

2. I am planning to do the test with 2 large slide-outs in the open position. Would the air seal be better in the closed position? I will be testing prior to campground turning on electric for the season so will use a generator for power and may have trouble if I need to close the slides.

3. Do I need to open something to allow air pressure to build between the trailer ceiling and trailer roof. If so, they would also need to do this when performing a Seal Test pressure test.

4. Is there anything I have wrong or am missing?

All advice appreciated! Thanks!

[Enzo_]

I’m very thankful for this thread. It really helped to perform a decent DIY leak pressure test.
My TT is 31’ long so I knew I would need a decent amount of air to gain enough pressure to find leaks.
In my case I used a high powered (2000 cfm) 14” tube fan ducted into a window as well as a leaf blower into another window. I cut down an old tarp to create the 14” duct.

My manometer showed approx 0.3 inch of water column movement which was enough positive pressure to find leaks using a soap and water spray.

I found about 10 leaks in total. 3 of the 4 gutter ends leak which is obviously not where you want water coming in. My 2 tail lights as well as one of the front seams also had decent leaks. I was happy that neither of the 2 slide outs are leaking, and none of the windows or 2 doors leaked. Roof was also good showing no bubbles.

Unfortunately for me, there is already significant water damage inside under my cabinets. I’m hoping that caulking my leaks and fixing the cosmetic damage will be enough. There is soft floor under the cabinets where nobody walks. I don’t plan on repairing the floor unless I notice the rot leaching.

Thanks again to all who posted here. Very helpful, and it potentially saved me $300 that my dealer charges for a seal tech test.

[SCClockDr]

Electric leaf blower? Seems I saw this discussed somewhere plumbed to a roof vent.

[j-d]

It'll take awhile to get this figured out and built. At first I thought I'd hard wire for fan speed, but reading the SealTech instructions, I need to add a four- (or at least three-) speed switch. The ST apparently uses a fully variable speed motor, but I'm sure one of four speeds will suffice for setting a proper testing pressure. Then the manometer. And of course how to mount and seal the blower to the coach.

I'd appreciate any and all suggestions about testing in general, as well as building this machine.

[westend]

Good luck j-d. Thanks for remembering this thread and keeping it alive. If it gets posted to, periodically, the information will still survive.

[j-d]

Update... After all these Years + Months, the BLOWER arrived on my doorstep yesterday. I think it's ideal. 1/3-HP 1075-RPM 115-VAC motor with Four Speeds. Uses a Run Capacitor. Out of a system being replaced. I tested it before dismantling to clean and all four work. Smoothly and quietly rearranged a box of aluminum cans I had in the garage to recycle. Blower Wheel is 8" wide by 10-1/2" diameter.

I think there used to be more threads, and Explorer's won't come up any more. Will start a new thread in awhile. Projects are stacked up, so this won't be making speedy progress.

[delad1954]

How can I help you ? I have been doing Sealtech leak testing since 2009..

[westend]

Good deal. You now have the means to check for leaks periodically. I'm surprised the air pressure bubbled the EPDM. Of course, who knows how much adhesive was applied, originally. I would think that the rubber will bond to the plywood again, given some time in the sun.

[Togger]

********UPDATE**********
Pressurization Success!

I made the trip to my trailer this weekend armed with the 1 HP CFM Pro 4200 carpet dryer. After covering all drains and vents with tape I ran the mouth of the carpet dryer through the bedroom hatch door and sealed it off with tape and cardboard.

I ran one end of a 10' half inch clear plastic hose through the cardboard and on the outside taped it to the trailer in a U shape with the hose touching above the U and poured water in. At the water level on each side I marked 1/4" above and below the the even water levels in the tubes.

I left a door open, turned on the fan, and gradually closed the door while watching the pressure. With the door all the way closed and the fan on low, I achieved .5" pressure difference in the water tube. This low setting was around 2600 - 2800 cfm. This is on a 40' trailer with 2 large slide in the open position and I did not do anything extra to seal the slides.

I mixed a strong dish soap to water solution of probably 1 part to 7 parts and started spraying seams and windows. I found some air leaks which were pretty evident even on a very windy day.

The tricky part is knowing where air should be leaking and where it shouldn't be leaking. All windows leaked air at the glass but I also found seams in the top of the aluminum window frames that leaked. I found a leaking caulk joint along the slide-out seal that shouldn't have been leaking. After rinsing off the soap and allowing to dry I sealed these spots.

WORD OF CAUTION: After over an hour of pressurization, spraying and searching for bubbles, I climbed on the roof and was alarmed to see air pockets forming between the rubber roof and the wood roof under it around several of the the roof vents. I shut off the blower and pressed these spots back down and the air pockets went away but the rubber is no longer glued fast to the wood in those spots. This occurred at exactly .5" pressure which is within spec for the Seal Tech machine instructions so I was very surprised that it happened. If I were to do it again I would keep the pressure down in the .3" range for a rubber roof.

Time will tell whether I got my leak fixed but I am optimistic at this point. If not I will go after it again. I hope my experience can help guide others who are dealing with similar frustrating water leaks. Westend, your pictures were very helpful. Much thanks to all who helped me with information in this thread.

[BurbMan]

Togger wrote:
From the spec sheet for Dri-Eaz air movers:

Sahara Pro X3 .25 HP 2700 max CFM. 1.28 max static pressure
Sahara HD 1.0 HP 3500 max CFM. 2.75 max static pressure

westend wrote:
STR a Forum member that used the Harbor freight $80 Portable ventilator with success. Again, just from a foggy memory, he had a plastic duct and introduced the air into a storage compartment. I'll try to dig up that thread.

The Harbor Freight Model is rated at 45 cmm which equates to 1589.2 cfm, and static is 480Pa.

[westend]

The plastic screw channel insert pulls out and is replaced easily. The screws can be a leak point so the insert cover should be removed when testing.

[j-d]

That vinyl strip is for looks (covering screws) and not waterproofing. RV Tech pointed out that water can run all the way down that channel, guided by the vinyl, where it can look for leaks at every screw.

[Cloud_Dancer]

Togger wrote:
I also have a question regarding spray checking for leaks once I acheive a positive pressure.

One area where the leak could possibly be coming from is the joint where the rubber roof meets the aluminum gutter at the sidewall. Above the gutter there is a plastic D shaped cover piece that runs the length of the camper and covers the screws that hold things together.

Would it be necessary to remove the plastic cover of the joint to be able to pinpoint exactly where the leak is? If I do remove it, can the plastic piece be re-used and put back on or would it need to be replaced with a new one?

I'm thinking I would leave the plastic cover on but if I get bubbling anywhere along it I would have to remove it to find the specific screw or spot that leaks. Any insight to how this joint is assembled would be appreciated because I'm not sure how that seam is constructed.

I can relate to this situation, as I'm slowly running out of places to look for the leak(s) on my Dutch Star.
I know that removing the plastic strip that covers the screws should not be a problem. You can buy this in a roll, or perhaps by the foot. I Googled RV roof rain gutter and screw cover. Keep searching on the internet and you'll find related general information and suppliers.

[Togger]

I also have a question regarding spray checking for leaks once I acheive a positive pressure.

One area where the leak could possibly be coming from is the joint where the rubber roof meets the aluminum gutter at the sidewall. Above the gutter there is a plastic D shaped cover piece that runs the length of the camper and covers the screws that hold things together.

Would it be necessary to remove the plastic cover of the joint to be able to pinpoint exactly where the leak is? If I do remove it, can the plastic piece be re-used and put back on or would it need to be replaced with a new one?

I'm thinking I would leave the plastic cover on but if I get bubbling anywhere along it I would have to remove it to find the specific screw or spot that leaks. Any insight to how this joint is assembled would be appreciated because I'm not sure how that seam is constructed.

[j-d]

I've had my eye on that HF Blower for awhile and was considering using it with the duct HF also sells. I've been skeptical of its capacity to pressurize the RV adequately. Would love to see a thread where somebody's used it and was successful.