# Capillary action and plastic cap nails



## Phillip (Aug 24, 2018)

I’ve been reading time and again how roofers are commonly using either staples or roofing nails with roofing membrane material 

Manufacturers are clear on requiring plastic cap nails but roofers ignore the instructions usually with comments that they are driving a thousand nails anyway so they aren’t needed.. or talk about the timeline

The easiest way to see capillary action is to stick a bit of paper towel on your coffee and you’ll see how the water defies gravity. It does not care about slope 

Place two sheets of glass together with one drop of water between and it won’t dry it will remain there 

Sheets of plastic laying together will also display capillary action in the same way

The old roofing felt was somewhat permeable over time and wicks away moisture 

The newer membranes are basicly plastic sheets albeit with a bit of porus material on top 

Two planks sisters together will also entice water between and this causes rot

If a carpenter builds outdoor stairs he willleave gaps otherwise the cracks suck the water in 

The plastic cap nails are shaped as they are for good reason they could be discs that are flat but they protrude for good reason. The gab breaks the cPillary action allowing a way for the water to leave. Otherwise it is like the plastic or glass sheets they can’t give up the water through evaporation or absorption 

Omitting the plastic caps causes large areas where the shingles and the plastic membrane are in contact thus holding moisture between. 

They aren’t simply there to prevent tearing. These gaps are there for good reason. They allow spaces where the capillary action is broken thus allowing evaporation to take place. 

Just because the water drawn up between the shingle and the membrane is only thin, it still has the power to degrade the roof sheeting if it remains there without space to exit. 

With old style felt it was a different situation because it allowed water to wick through at least somewhat when you replace that with a sheet of plastic now you need the gaps. 

I know it’s faster but it’s wrong and encouraging the practice may get you jobs as you appear more competitive but they are called for for a very good reason


----------

