Just Say NO! to Thin-Walled PVC
By: Patrick Hooper
If you’ve read any of my blog or facebook posts about substandard pipe–which you can find here or here–you are aware of the serious problems associated with using weak, inferior pipe material for underground drain line.
After having the front gutter on my house re-pitched (reversed) and a downspout added to accommodate the redirected storm water, about 40 feet of underground drainline needed to be installed to divert the storm water from our front yard to the back yard. After digging the trench, it was off to our local hardware store to purchase 40+ feet of 4-inch SCH 40 PVC pipe and fittings.
A
s I was loading the 10-foot lengths of SCH 40 pipe onto my cart, a very nice and well-meaning store employee approached me and asked what the pipe was for. When I told him I was laying an underground downspout line–he pointed out that the thinner-walled PVC pipe at the the other end of the isle was made specifically to be used as downspout line and was also much cheaper. “Cheaper than what?“I thought to myself. Cheaper than having to dig it up and replace it after it collapses? Cheaper than repairing damage in the basement from storm water funneling to the foundation caused by a crushed and backed up downspout line?
Of the hundreds of video inspections I’ve performed, I have never seen collapsed SCH 40 PVC–whether used as 
sanitary or storm/downspout line. Corrugated/flex pipe, thin-walled PVC, smooth, single- or double-walled PVC, etc.–all of which I see being used most of the time as downspout line– is more likely than not to be compromised at some point–if not fully collapsed.
Does this mean you should not consider buying a home with thin-walled PVC downspout line? No, not necessarily. Unfortunately, cheaper, light-weight pipe material is very common, especially in newer construction. Should you hold out until you find a house that has SCH 40 or even SDR 35 PVC, you will likely be looking for some time.
Builders/developers manage their expenses to keep their overheads low. Unless otherwise specified, they will likely use the least-expensive materials approved by construction code to maximize profits while making the houses as affordable as possible. To use an automobile analogy–when buying a house, it is not unreasonable to expect to have to eventually replace/upgrade some of the factory parts at some point. Contractors that offer to make those upgrades (repairs) and use the same substandard parts they are replacing may not have the best interest of their customers at heart.
The definition of insanity is doing the same thing over and over again and expecting a different result. I’ve heard the argument that as long as the weaker, thinner-walled pipe is installed correctly, it will be fine. Well, then nobody must know how to properly install this stuff because in my experience, failed thin-walled pipe is the rule, not the exception. But, I have yet to see broken or collapsed SCH 40 PVC.
