If I understand this correctly, there are (2) systems? I would look at the RP-265/baseboard system. If you are moving over 280 cfm, some of that is basement air. Any air being pulled from the basement is fighting against you. Try rechecking your pressure field extension with the baseboard system off. If you have a significant increase in the pressure drop, try retesting it with the baseboard system off. You can also consider temporarily replacing the switch with a variable speed control to imitate the performance you would get by installing a smaller fan on the baseboard system.

I have an old RP-265 that we use to check for leaks. We mount it upside down and attach a coffee can with holes drilled in the bottom. Then we drop a smoke bomb in the can and blow the smoke back into the system. Mark any areas that smoke appears in the basement with painters tape. In this case, I would seal any leaks and repeat the process. You may find that once you seal the major leaks there is still significant suction loss thru smaller holes.

You could also consider installing a suction point closer to the center of the slab on the GX5 system. If you are applying suction 4 to 5 feet from the foundation, you may be losing some suction under the foundation. if none of that produces satisfactory results, try repeating your "salad bowl" test in any areas that have an upper slab like a patio, garage or addition butting against the foundation.

Good luck!

Shouldn't you have a "Temporary Installation" sign? If nothing else, it would help me get past the pipe being so far out of plumb!

The best time to spray a nest is at dusk, when they are all back in the hive.

I would use polyurethane. Make sure the concrete foundation is clean and free of dust and form oil. With the extra weight of the 12 mil membrane, you may need mechanical fasteners as well.

Thank you Kevin. MSDS are available on the manufacturers website or you can pick them up at the store where you are purchasing the materials. I've found that putting them in plastic sheet protectors in a 3 ring binder behind the drivers seat with the first aid kit works well, and adding new products is simple. Having them on the van is handy if the homeowner has questions.

We use urethane for suction points, control joints and any other places that we want to be sealed permanently. We use 100% silicone for sump covers and any other locations where future access may be required. 100% silicone is easily pulled off a Lexan sump pit cover. It comes off like a big rubber band. If you're trying to unseal a sump lid sealed with urethane, you'd better have another cover with you, and do it before the children get home from school!

I believe the manufacturers data stated their urethane "bonds tenaciously to most substrates". I'm here to confirm that. I had a home back in the late 1980's that I had covered the basement access opening to a cross vented crawlspace. I used the "radon barrier" membrane that was black on one side and white on the other. It had a ton and a half of tensile strength per square inch. I sealed it as part of some waterproofing work because the owner complained about a musty smell coming from the crawlspace. I cut a piece of the membrane several inches bigger then the opening, caulk around the opening, and pressed the membrane flat onto the wall. Several years l later they were selling and I was called back to install a radon system. In order to install a membrane on the dirt crawlspace floor, I had to remove the seal. The urethane actually pulled the face of the concrete block off where it was attached.

I would expect both products to be impermeable to anything that doesn't degrade it. As far as fumes, I like the solvent glue the best!

Thank you Nicole. For those not using public transportation, any word about the status of gas stations in the area would be helpful. Yesterday I heard a report that lines for fuel were still hours long.

In all my years of mitigating, I have never had to seal a stone foundation to successfully mitigate radon either Dick. I'm thinking it's more science than luck!. A stone wall has no footer, instead relying on the width (18-20" in South Central PA) of the wall to bear the weight of the structure above it. Without the footer to contain your negative pressure field, your often depressurizing the soil on both sides of the wall.

For weatherization, I strongly recommend a spray foam applications with a spray coat of intumescent paint. Hanging a vapor barrier from the sill plate would violate fire code and provide a concealed moist pathway for termites.

Best wishes,
Jay Bauder

We typically cover non-standard sump pits with Lexan. We mount a 6x6 PVC utility drain (no bell trap) with an 1-1/2" PVC trap mounted to the underside of the cover Often a hand dug pit is located at the low spot where water would puddle. An 1-1/2" drain will handle large amounts of water without clogging. I would caution against sealing or lining the pit with concrete. Sometime the water problem that inspired the pit was a result of ground water or hydro-static pressure. Sealing the soil may cause the water to find a new entry point resulting in a water problem that you created. The best option would be to install a perforated liner with a Lexan cover and floor drain.

If there is a pedestal sump pump, I give the owner the choice of replacing it with a submersible sump pump before we arrive or paying us to replace it at the time of installation.

Thank you Larainne, that is condition I never would have considered.

The staining on the framing seems to indicate that the roofer also wasn't at the top of the class. Kozy Kollar should make a roof plug flashing for moments like this. One with a big wingnut, similar to a plumbing test plug.

https://www.lowes.com/pd/Oatey-4-dia-PVC-Test-Plug-Fitting/3880611

We have had success with Krylon Fusion (made for plastics). I strongly agree with Dick that painting the piping after installation is best. Any paint on on the solvent glue surfaces will hamper the assembly of the vent. Painting the piping several months after installation allows the suns UV rays to break down the oils used in the manufacturing process of the pipe, fittings and rubber couplings. Make sure if you paint the fan to protect the fans label for the purpose of later fan identification and/or warranty claim.