New Capped Composite Decking Advances Again
What Do You Need To Know About Capped Composite Decking Boards?
The latest advancement in the composite deck category is the concept of capped boards. Its also called capstock decking.
These are essentially composite boards with the wood plastic core
but have an impervious layer of textured plastic around the board.
This skin now covers just the top or three sides with the bottom side uncovered and free to breathe.
The concept of encasing the more vulnerable wood fiber plastic core makes good sense.
These durable skins can really be made to stand up to sun,
staining, mold, bacteria and all kinds of other environmental predators.
They can also be textured and colored for quite stunning visual
effect. All of this is good and are things consumers have always wanted.
They are more expensive though and some of the higher end capped
composite decking gets into the $4.50+ per foot range.
Some of the hardwoods can be purchased for this range and they are the real thing and almost indestructible. And there is one I really like.
Ends of boards could expand and mushroom.
This is what many builders unfortunately found out in the very
early days of this new material. It seemed that the more the board was
encapsulated, the less it could expand if water was absorbed at the
With the older style boards, water could be absorbed all over and
the board would expand widthwise and lengthwise freely and then shrink
when dried out.
But especially with boards that were covered on all four sides, the ends of the boards were mushrooming when they got wet.
Imagine the wood core is like a straw and sucks in the moisture if
the end gets wet but there is no where for the expansion pressure to
escape, except out the ends of the boards. Consequently, there were some
horror stories of boards expanding sideways at the ends. And worse yet,
they never went back to normal.
Now it is quite possible that the phenomenom is greatly reduced if
the board is only covered on the top surface and/or the sides.
But certainly this is why you will see now that the capped composite
decking always has an unsealed bottom and usually partially unsealed
sides as well.
Clearly, the attempt is to stop this from ever happening again and allowing the board to breathe and expand when wet.
Still A Big Improvement
The open bottom that lets the board breathe and move seems to be working.
Despite these early issues, I think as long as you are aware of what
caused the original problem and can satisfy yourself that the open
bottomed boards are able to allow for explansion in the event the ends
get wet, you will be fine.
There you have it. A nutshell on the good and what was not so good on
capped composite decking. If a composite board is not your preference
there are many other materials to choose from.