Taping house wrap

[Wayne Whitney]

Hello,

I understand that with a plastic house wrap like Tyvek, the seams should be sealed with a wide sheathing tape. Does it make sense to do when using 30 lb felt paper as a house wrap?

Cheers, Wayne

[Robert Allison]

No. You are going to have a very difficult time finding any kind of tape that will stick to felt for very long.

[Edwin Pawlowski]

No, you can't tape felt very well. Why would you as it is not going to perform as well as Tyvek. Building a second rate house?

[Wayne Whitney]

There is some debate as to whether plastic house wraps outperform felt. See, e.g., the first google hit on "house wrap comparison":

In the absence of compelling evidence that plastic house wrap is superior, I'll stick with the tried and true. I will be using Home Slicker under cedar sidewall shingles to provide a positive drainage plane, that is an invention that makes alot of sense to me.

Cheers, Wayne

[Wayne Whitney]

OK, just to be clear, I understand plastic house wrap is an air barrier, and that is taped at the seams to provide better infiltration protection. Is 30 lb felt also a good air barrier, and so would sealing the seams (if possible) also be beneficial? Some plastic house wraps suggest caulking the seams as an alternative to taping to them, would this be an option with felt?

Thanks, Wayne

[Robert Allison]

Not really. You would have a hard time doing this, also. The caulking procedure would be hit and miss due to the felt being pliable. If you tried it, you would see what I mean.

When we want to get a more secure application of felt, be simply overlap more. If you double lap the felt, which means that you lay the felt halfway down the previous run, you get a double layer of felt. This provides a better alternative than trying to tape or caulk. Sometimes we double layer the felt for additional protection, although this is most often done on roofs (as in a low slope situation).

If you are really worried about this, you should just use housewrap. It will act more as a air barrier than the felt, although both will perform for moisture protection. I have torn off siding that has been in place for over fifty years and found the felt behind it brittle, but still in good condition.

Keep in mind that I am not a proponent of housewrap. I use both for differing purposes and kind of use them interchangeably on walls, depending upon the application.

[George E. Cawthon]

I think you are asking the pros and cons of house wrap and felt. Felt has been used for years and can do a good job, since it is a barrier to liquids and gas. Heck if you put on felt but don't cover it with siding, you have a tar paper shack (might be a very big shack though). Since felt is always overlaped, it sheds water and depending on how the siding is applied it may also allow moisture to move through the overlaps and still be a very good barrier to air flow.

In contrast, Tyvek shed water but allows moisture to pass through, but stops gross air flow if applied correctly (taping joints and all holes). Tyvek essentially prevents all air inflow, but it allows moisture in the form of gas to pass through. That supposedly helps keep the insulation drier by allowing the moisture to move to the outside.

From looking at a large number of housed under construction, I would suggest that the construction is far more important that the material used. I've seen Tyvek with holes, rips etc. that would allow all kinds of air inflow. The same is true of felt applications.

[nicksanspam]

Yes. It can cause condensation and rot if used outside insulation on a house in a cold climate. I've read new houses in Minnesota have fallen down after

5 years because the studs rotted inside the vapor barriers.

Nick

[Wayne Whitney]

Yes, I understand plastic house wrap will trap liquid moisture, so vapor that condenses inside it will not be able to escape. That is why I'm going to use 30 lb felt. Felt will slowly absorb liquid water and then allow it to evaporate as it it dries. Drying will be aided by the Home Slicker drainage plane I plan to use between the felt and the cedar sidewall shingles.

But, the question I have is whether it would be useful and feasible to seal the seams between courses of felt. So far I have heard it is not feasible with tape, as tape will not stick to felt very well. Still, would it be useful to seal the seams? That is, are the seams a comparitively large source of air infiltration, relative to the felt itself? If so, is there some other way of sealing the seams?

Thanks, Wayne