Humidity in spring vs. summer

Old 05-11-21, 07:20 AM
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Humidity in spring vs. summer

Hi. I wanted to start a new thread rather than following up my old one (as the topic of the old one keeps changing a bit).

I recently had my crawl/walk space spray foamed, and my basement refinished (outer walls spray foamed as well).

Even w/o my santa fe dehumidifier running yet, the humidity in the finished spaced has hovered between 55% and 65%, sometimes touching 70%, but the RH hasn't gone above 65% in the past month, even during heavy rains and periods of several days of wet weather.

In the crawl space it's been roughly similar to the above as well.

Is there any way to know how this might translate to the summer, when outdoor temps will be warmer (though temps in crawl space/basement may not move much?), and higher humidity in general (again though, during rain/wet periods recently it's been ok).

I was hoping that the spray foam did the trick and may keep the humidity at safe levels, and therefore wouldn't requiring cutting vent holes into the finished space (santa fe is in boiler room and in the past we had 2 vents cut for air circulation, which we'd of course prefer not to do in our nice, newly finished basement).

Or is it simply impossible to gauge how the summer weather may affect the humidity levels as compared to right now (I'm assuming this is the answer)?

Thank you.

Old 05-11-21, 07:29 AM
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Your indoor RH is proportional to the outdoor RH, everything, with time, will balance out but the presence of insulation will slow the rate of change.

Just like my conventional finished basement, it's much dryer in the winter than the humid summer!
Old 05-11-21, 09:00 AM
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Your spray foam is likely a closed cell and will block the movement of most moisture through the walls and floor above. That can be good or bad depending on conditions. If the humidity is low outside it will hold the humidity higher in your crawlspace and if the humidity is high outside the foam will block much of the moisture from entering.

Generally summer's higher temperatures and less rain means lower humidity so moisture will slowly migrate out of the crawlspace albeit at a pretty slow rate since you've essentially vapor barriered your crawlspace. If you want to lower the humidity in the crawlspace a dehumidifier or ventilation will get the job done much faster.
Old 05-12-21, 02:01 PM
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Thank you.

On a separate but related note, assuming I do need to continue using the santa fe and condensate pump (both of which have to be moved due to the work we had done, is it ok/safe enough to use an extension/hose clamps such as this:

or is it too risky and I'm better off buying a longer tube, but then I'd have to run that tube all the way outside (either drilling a new hole or seeing if I can remove existing tube (which is now too short) and using the same hole. I'm sure it's not easy to use same hole as they likely sealed it pretty well, plus it runs through the crawl space plus I'm not going to drill through the house myself so I'd need someone to do it for me.

hence i'd much rather just use the extender/hose clamps.


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