The Front Door Light Block Story
Every year, Connolly Construction Co. is asked to replace rotten exterior trim and siding installed by others. The exterior wood trim replacement request is so common we felt a short story on the topic might be of interest.
Why does trim rot? How can you prevent it? What should you do when you have it? We’ll address these questions using examples from a recent front door light block replacement job in Darien, CT.
Why Does Exterior Wood Trim Rot?
The main reasons are: (i) it’s wood and it’s life cycle is analogous to that of humans: it is born, it lives, it ages, it dies (with exterior trim, this is known as harvesting trees by wood processing companies) and eventually it decays and decomposes (thanks to various fungi); (ii) if not maintained, water and related fungi (aka mold) will infiltrate the wood grains and start the rotting process sooner and faster rather than later and slower; (iii) in all cases that Connolly Construction has repaired or replaced over the past 20 years, lowest cost initial material selections combined with incomplete or shoddy initial installation techniques contributed to early and accelerated rotting of the exterior wood trim components.
How Can You Prevent Rot On Exterior Trim?
(i) You can purchase exterior trim that is synthetic, not wood. The synthetic product is known as pvc trim. PVC stands for polyvinylchloride and these 6 confusing syllables can be shortened into a word that is simple and easy to remember: fiberglass. Fiberglass does not rot, or at least not very fast.
But be careful. Since it doesn’t rot, pvc may disguise the telltale signs of rot that are easily visible on wood trim. It may disguise the fact that water is migrating behind the pvc trim and rotting the wood framing members underneath and the paper components located on both sides of the sheetrock and fiberglass batt insulation within your wall cavity.
If you don’t spend more to hire a talented and careful carpenter to install the fiberglass trim correctly, (ie. one who understands and properly installs flashings and drainage planes around and behind the pvc trim) in 5 years or less you may end up spending thousands to repair water damage to the house components located beneath the pvc trim. If you elect not to pay more to get pvc installed right, you’re better off spending hundreds to simply replace the old rotten wood trim with more wood trim. At least by taking the lower cost approach, the next time your exterior trim rots (which will probably be within 3-5 years if you use pine) you’ll be able to see it and address it before it spreads to the inside of your wall cavity. (The way to install pvc trim correctly is a separate story for another time.)
(ii) You can purchase decent wood and related materials up front and pay more for an installation done right once. This will probably mean that you won’t be able to select the lowest bidder to perform the work. To bid low, most installers will have to use materials that are often acceptable (eg. conform to code) but are lowest cost and therefore least likely to last the longest. And they’ll have to skip some steps to save time and money in order to bid low. Examples of lowest cost, incomplete work and skipped steps follow in the case study below.
What Should You Do When Your Exterior Trim is Rotting?
The simple answer is to repair it (with a filler patch or a graft of new wood) or replace it. But don’t wait. The longer you wait, the more it will cost to remediate. When it comes to rot, Mother Nature doesn’t wait to start and shows no mercy once under way.
The Darien Case Study: Trim Replacement.
When replacing 2 light blocks, which are a form of exterior trim, to which the front door entry lights were attached on a home in Darien CT., we noticed some deficiencies in the old work.
– The drip cap step was skipped. There was no drip cap on the top of either block. A drip cap is a piece of flashing, usually aluminum, which diverts water away from the openings cut through the exterior skin of your home (to make way for windows, doors and light blocks). This step is often skipped by installers because: (i) they don’t have the right drip cap in the right dimensions in their truck that will fit your trim and making a special trip to the lumberyard to get one wasn’t included in their low bid budget; or (ii) it’s too hard (i.e. too time consuming for reasons unrelated to travel time and therefore unprofitable) to fit one in; or (iii) they don’t know any better. In many locales the absence of a drip cap is not to code and thus would not pass a building inspection.
Take a look at the new aluminum drip caps cut to fit on the top of each new light block in the photographs below.
– Caulk Was Used In Lieu of a Drip Cap. In the case of the Darien project, a really wide and deep joint of caulk was used on the old work in lieu of a drip cap or other flashing method on the top sides of each light block. We see this all the time: caulk in lieu of flashing. It is a pernicious short cut, particularly when a foam backer rod is not used (as was the case here) when using caulk to fill gaps that are over 3/16” wide and deep.
Caulk usually fails in a year or less. It does not stop water very well, particularly after a year. It opens up or cracks or degrades or moves over time. When one or more combination of the foregoing occurs, water will migrate through or around the caulk to penetrate whatever is underneath. The only reason to use caulk is as a decorative surface for paint. Good flashing and drainage plane installation, not caulk, is the only long term solution to addressing exterior water management issues on exterior trim and siding.
In the case of the light blocks, caulk was used to cover up some questionable carpentry and as a substitute for a drip cap. Caulk was a cheap and easy way to make the work look good. But it failed eventually. Water traveled through and around it to the backside of the light block contributing to the swelling of the wood grain. As the wood grain opened up, water traveled into the “cracked” openings in the wood and the rot process intensified and accelerated. Connolly Construction came on board at about the time paint was peeling. The peeling was due primarily (though not exclusively) to the higher than average swelling/shrinking cycle of the wood, which in turn was related to the higher than average swings in the wetting/drying cycle. These conditions all made paint adhesion difficult.
Take a look at the old light blocks in the photos below, identified with blue painters tape. You’ll see the swollen, cracked wood grain on the old blocks. The block without painters tape is the new one fabricated by Connolly Construction and is made from tight grain, no.1 cedar and painted on all sides prior to installation.
– Least expensive materials were used. The old light blocks were made from no. 2 pine. This material has wide horizontal grains and knots, which open up when wet and allow water to penetrate and ultimately rot it with ease. At 7.25” wide and 1” thick, it costs around $1.25 per lineal foot. But only 3 lineal feet are required to make two light blocks. For around $5 per lineal foot, or for an extra $10 or so, we purchased tight grain, knotless no.1 cedar and fabricated the blocks to fit into the existing openings in the siding. Even when not painted, cedar lasts longer than painted no. 2 prime. Wouldn’t you rather spend an extra $10 to get something that will last?
The photo below shows a piece of the high quality cedar on the cutting/painting table in process of being further cut and shaped by Connolly Construction.
– The paint step was incomplete. Take another look at the photo below and note the differences in the paint preparation of the materials. The old material, identified with blue painters tape, was only painted on the front and back surfaces. It was not painted or primed on the sides and on the interior of the circle cut out (for the light fixture attachment plate). This is a huge omission. And we see this all the time in exterior trim contexts. One or more sides of the trim are not primed and painted. This omission shortens the life of wood products.
Shouldn’t all six sides (and more if there are “carve outs” such as appear on the interior circle of the subject light blocks) be painted to protect the material from the elements? Of course. Water will get around and behind the visible painted surface of the wood and start to rot the sides that aren’t visible and usually are not painted.
So why do carpenters skip the step of painting all surfaces of the wood? Unethical technicians skip the step because it’s hidden and no one will know. Other reasons I’ve observed is it’s messy, it slows down the work flow, the installer may not be getting paid to do it (particularly if they are the low bidder), they may not know any better or they may think it makes no difference. Since most sides of the trim are concealed from view, carpenters know that any latent deficiencies are unlikely to appear within the one year warranty that is often offered. So many installers make the mistake of concluding: ‘why bother to take the time to do it right when no one will see it?’ My advice to you is you and your remodeler need to bother if you want to save money.
If you’re going to use wood exterior trim products, make sure you insist on and pay for carpentry that includes priming and preferably painting all 6 (or more) sides of exterior wood trim PRIOR TO INSTALLATION. If you don’t, be prepared to pay more to replace it in 3-10 years.
– There was a large hole in the wall sheathing adjacent to the light plates.
To make way for new rough in work (ie. the work you don’t see that’s inside the walls or covered up with plumbing and light fixtures), plumbers and electricians often cut holes into framing lumber (eg. to accommodate plumbing traps or new light plates). Over the past 20 years, Connolly Construction Co. has noticed that the vast majority of these holes are much larger than they need to be to accommodate the new rough in work.
Following completion of the rough-in work the excess material that was cut away is usually not patched or repaired. There are a variety of reasons for this. The most common is that licensed pros are often in a rush to complete their work. This is related to the fact that their low bid, which the homeowner readily accepted to save money, does not cover the extra time needed to do the work right. To make money, they have to finish fast. To finish fast, they have to skip steps and closing up the hole properly is one of the steps that usually will be skipped to save time when pursuing profit on a low bid.
The downside to you of this practice (ie. the failure to close up and air seal the holes) is that large amounts of heated air in the winter and conditioned air in the summer will escape through these holes, increasing your heating and cooling bills. Also, if the holes are located adjacent to unheated cellars or exterior walls, liquid water and water vapor will migrate through the holes and into the framing and other building components creating mold and accelerated rot, which have health and financial implications. The money that was saved by accepting the low bid up front will be more than eliminated by adverse effects, mostly unseen, after the work is completed.
Take a look at the photos below to apply the foregoing general principles to the case study. You will see areas of cured yellow spray foam that were installed by Connolly Construction to seal the holes in the wall sheathing. This will protect the home from both exterior water and air infiltration and it will help to seal the home so that interior hot and cold air will not escape, at least through the foamed areas.
Waiting for the foam to cure. It’s a little hard to see the spray foam in the replacement areas. But this photo gives you an idea of the context. See the next two photos for close-ups of the foamed over holes.
(One side note: Connolly Construction installed new pvc trim around the right side of the entry door, to match the profile of the wood trim on the left side of the door, which remained in place. All was repainted to match.)
Conclusion: Spend $100 to Save More Than $400?
Had relatively minor adjustments been made up front when choosing materials and labor techniques (of approximately an additional $100) the light blocks that were installed less than 10 years ago would not have needed repair or replacement today. Instead of paying an additional $100 for the work up front to produce a longer lasting installation, those who have followed the original owner elected to spend over $400 to replace the work. This is not a green or sustainable way of going about construction. Twice as much material and labor was used over a relatively short time horizon than was necessary. And this is wasteful.
If you plan to stay put for awhile, wouldn’t you rather spend $100 to save $400 (plus even more savings on heating and cooling bills when the holes in the wall are closed up)? Hopefully, there is enough information here for you to make intelligent choices the next time you spot rot on your exterior wood trim.