Tar paper trouble

[dougpete]

We used tar paper to wrap our 24 x 34 two story, but on the south (full sun side) the tar paper shrunk and tore itself loose.

What did we do wrong? 

Also, what should we use to flash window nail flanges to the tar paper?  Should we just do over with house wrap?

Doug

[rocking23nf]

I had the same experince with tar paper on my roof, once the sun and wind hit it, it was done for.

I ripped it all off any put ice shield down.

[JRR]

Eventually the elements will take tarpaper down.  But the life can be improved by using heavier paper and better fastening.

Tarpaper (felt) is commonly available in 15# and 30# weights, the 30# being more durable.  Fastening is best done with the special nails with plastic washers ...  the more the better.   I like to add a bead of roofing sealant (caulk gun) under the edges to keep the wind from lifting the paper.  A well fastened paper will endure a lot of weather, but if you expect a great deal of service... perhaps roll roofing should be used instead.

[MountainDon]

How was it secured? Button cap nails work very well when used in sufficient quantity especially along the edges where wind might get under it. Pull it tight. It's impossible to do by yourself.

Windows and doors should be flashed with something like Grace Vycor.

http://www.na.graceconstruction.com/custom/flashings/downloads/26324_Guide-B.pdf


Yes there are two weights of felt but #30 is really meant for roofs. It is too stiff to use for walls as far as I am concerned. Number 15 is fine when nailed right.

[Don_P]

Tarpaper is really not meant to be left exposed for very long, the sun is tough on it. Yes I've left it up for months on a roof but it losses much of its effectiveness.

Paper is made from wood fiber, when wetted it swells, when dried it shrinks. This is part of what makes tarpaper work so well and also what makes it a bear to deal with at times. When dry the tar impregnated fibers have many pores that allow vapor to pass through. When wetted the tarred fibers swell and slam the pores shut, repelling liquid water.

[davidj]

Around here (Northern CA) we have felt for the roof (#15 or #30) and building paper for the walls (rated 10 minute or 60 minute).  60 minute building paper seems roughly similar to #15 felt but I'm guessing the building paper breathes more than the tar paper (as exterior walls typically are designed to breath more than a roof).  It's also less brittle than the felt but it still gets pretty bleached-out and beaten up after a few months of exposure.