Author Topic: Humidity in new home  (Read 2142 times)

Offline danv

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Humidity in new home
« on: February 24, 2015, 04:10:26 PM »
I installed a honeywell 12 gallon bypass humidifier in a new townhome north of Toronto a few weeks back. Home owners called the builder before I came in because floors we're cracking/opening. When I got to house humidity was at 25%.

Got a call today from home owner with builder representative. Builder representative said out of all the homes he has checked this is the only home without condensation on the windows so they will not be correcting his floor issue. Home humidity was at 40% today according to the humidistat mounted on R/A duct. I will be going to home tomorrow.

wanted to know, Is there a code in ontario for RH in a home? Anyone have suggestions?

Offline Admin

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Re: Humidity in new home
« Reply #1 on: February 24, 2015, 05:32:57 PM »
The builder is not honoring the hardwood flooring warranty because there is no moisture on the windows?  I assume the floors were already cracked before the humidifier was installed?  The builder would have to prove the RH was kept below 30%, but from what you're saying the RH has been 40% since the humidifier was installed.

If the builder has already documented an RH of 25% before the humidifier was installed, and now the RH is at 40% since you have installed the humidifier, why are you going back?

I would refer the builder to the Honeywell HE225 manual.  See the attachment.  At -20C the humidistat should be set to 25%.  If the client follows the humidifier's instructions then they cannot maintain between 30-50% RH to protect the hardwood flooring warranty.

Builders and homeowners are upset when there's moisture on the windows, as this could mean there's also moisture and mold in other parts of the home, and they are upset when the house is dry and the floors crack.  We can't have dry windows and an indoor RH above 30% when it's colder than -20C outside, unless we use an automatic humidistat with an outdoor sensor.  If the control has built in window frost protection technology you should be able to avoid moisture on windows and never drop below 30% RH.  Keep in mind there is no avoiding moisture on windows when the outside temperature changes drastically.

There are no codes regarding humidity in Ontario.  The Tarion Construction Performance Guidelines is the only real document you can refer to.  See Section A2 Moisture in Wood and Laminate Floors.

Wood and laminate flooring will perform best when the interior environment is controlled to stay within a relative humidity range of 30 to 50 per cent and a temperature range between 15°C and 27°C.

There seems to be a discrepancy between the humidifier's instructions and the hardwood flooring warranty requirements when it comes to indoor RH.  Regardless it's not an HVAC problem.  It's a builder problem.  Your humidifier has increased the RH by 15% well above 30%.  If the builder claims the hardwood was already damaged before the humidifier was installed, then that argument is between the builder and client.

In my opinion the best thing to do is ignore the humidifier's instructions and leave the humidistat set to at least 30%.  The client can complain about moisture on the windows, but at least the hardwood flooring warranty won't be compromised.  You then refer them to Tarion Section 8.5.  Also beware of the hygrometers the hardwood installers or builders leave with the clients.  I have yet to see one that actually works.  They all seem to show an RH below 30% even when the RH is higher.  I've always suspected this was a ploy to avoid having to repair hardwood.  Ask to see the builders hygrometer and compare it's readings to the humidistat you installed and your own hygrometer.  Trust me, you will see that the builders hygrometer is reading lower than the actual RH.

If you installed the humidifier properly and you advised the client to follow the humidifier's manual regarding the humidistat settings, then you did your job.  The builder cannot blame the client for following the humidifier's instructions and lowering the RH below 30% on cold days.

See this thread on humidity here,

Offline danv

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Re: Humidity in new home
« Reply #2 on: February 24, 2015, 06:30:49 PM »
Thanks for the detailed reply.

The builder did not record the 25% humidity. The home owners originally called the builder due to some separation of wood floor, the builder suggested the humidifier in which they called me and my psychrometer was giving me 25% RH in R/A.

I'm going to print out section A2 of the  The Tarion Construction Performance Guidelines and give it to the home owners. I am sure that the builder is finding anyway possible to avoid it's warranty. I was baffled when he told me this was the only house he has seen without condensation on windows.