Keeping insects out
caliberger
| Posted in General Questions on
I’m planning to use an exterior wall assembly consisting of cement fiberboard, furring strips, housewrap, and sheathing
The cement fiberboard detail can be seen here http://www.wkarch.com/catalog/northbrook/
My only concern is insect nesting behind the siding
Any ideas on how to prevent this?
I am trying to stay away from reglet trim, which would solve the problem, for both economic and aesthetic reasons
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Replies
Hi Cali.
There are a number of methods for closing a rainscreen gap from critters while maintaining airflow and drainage behind the siding. Many builders use common window screen material, though some GBA users have pointed out that it is easily damaged by foundation plantings, so it comes along with a maintenance issue. Rolls of roof ridge venting are another option that can be easily cut into pieces and fit between the furring strips. And Cor-A-Vent and others make products specifically for this purpose. You can find info on this and other rainscreen details here: All About Rainscreens
Brian. What a pleasure to see your name at the top of the reply! I feel I know you well having listened to every FHB podcast with the original crew twice. Let me add that I heard you were thinking about restarting a GBA podcast and I think that would be fantastic! I have also saved the original GBA Radio podcasts and listen to them every so often to glean more pearls of wisdom.
Thank you for the helpful information you provided in response to my question. I will be reading the referenced article carefully.
Another question about my assembly pertains to a potential problem a builder friend pointed out. My home directly faces the ocean and the concern is that most housewraps would not fare well being exposed to high winds, salt air, and sun. Is heavy tar paper a good alternative or do you recommend abandoning the idea of leaving gaps between the fiberboard panels and simply plan on using reglet trim which would also solve the insect problem? Again, my reasons for avoiding the trim detail are aesthetic, saving money, and ease of replacing damaged panels
Hi Cali.
Thanks for the kind words. The Podcast was always fun to do and the new crew does an even better job with the information than we did, I think. I'd like to get a regular GBA Podcast going. Right now, it is a technical issue that is standing in my way. I have some technical help at Taunton HQ, just a matter of finding the time to get it worked out.
I am not aware of issues with housewrap in high wind areas once they are protected by siding. In your case, there would also be furring strips lashing them to the sheathing. But if this is a concern, you could consider a fully-adhered WRB or a fluid-applied WRB instead of a mechanically fastened housewrap. These products are more expensive to purchase but have the advantage of also providing your primary air barrier at the sheathing.
Cali,
What you are proposing is an open-cladding. The problem with that is that one of the main reasons rain-screens were developed was to take the burden of dealing with bulk water intrusion off the WRB, and off the back of siding. Open-cladding defeats those purposes. To compensate manufacturers now make more robust house-wraps for open-cladding, but that doesn't deal with insect infestations, or the additional water that ends up in the cavity. A long way of saying I think open-claddings are a bad idea, and would suggest springing for the reglet trim.
Thank you again Brian and thank you Malcolm. You've made a good case for using trim. Do you have any experience with this assembly or advice you can pass along?
Cali,
The Hardy-Panels and trim get use a lot here primarily on multi-family residential. I haven't installed it myself. https://www.jameshardiepros.com/products/hardie-reveal-panel-system
Hi Cali.
Sorry, I didn't realise that you were considering an open cladding system (thanks Malcolm). From the details in your question, I simply thought you were describing a common rainscreen assembly. I should have opened the link.
If you do go with the open cladding, look at Benjamin Obdyke or Pro Clima (475 High Performance Building Supply) for a WRB developed for these types of installations. Not only are they more UV resistant, they are all black with no writing, so they disappear behind the siding.
Malcolm- what is your opinion of Benjamin Obdyke's open-joint rainscreen system? Would you still suggest springing for the reglet trim?
Cali,
If you are set on using an open cladding it is probably the way to go.
Conceptually I lo0k at these assemblies as transferring the functions of their components back into the wall. The cladding is really a screen. The WRB becomes a cladding, rather than a secondary layer of protection. It all may work fine - although our code shares my view of them, and does not allow open-cladding in coastal BC.
Makes sense Malcolm. Thank you again
Since we live in similar climates, let me ask you an unrelated question. Do you have a recommendation for a large (10x12) sliding glass door in an oceanfront environment? We are remodelling our home and our current sliders have fared poorly. The rollers, track, and locking mechanisms are a constant maintenance issue due to corrosion. From an aesthetic standpoint, we prefer narrow aluminum frames.
Also, what is your opinion of lift and slide doors?
Cali,
No sorry I don't. I have had similar problems with sliding doors. The resort near me fights a constant battle with the same issues. I no longer specify them on any jobs. Good overhangs go some way to alleviating the problems, but most of my jobs are in rural areas surrounded by coniferous trees, so the tracks are always fill of debris - and I suspect that would make lift and slide doors problematic too. My solution when designing is to provide the desired amount of glazing with fixed window units and use a single exterior glazed door.
I see by your design philosophy you do not like call backs
:)
I'm pretty risk adverse.
Cali, no contractor likes callbacks. Callbacks are lost time and money. This is one of the reasons it can be so difficult to get anyone to try a new way of doing things — no one wants to be the test case and get stuck with a huge money-sucking boondoggle of a project if things don’t work out.
You’ll often find the better contractors to be the most conservative ones because they’ll have the experience to know what works and what doesn’t. In my technical consulting buisness, I tell people they are paying me for what I know, and for my design experiencing having done many prior projects. Customers don’t always listen to my recommendations, and that’s usually when they run into problems with their projects. Any experienced contractor will have similar stories.
Bill
Chances are if you build enough houses over the years there will be a few unanticipated problems. I'm happy to deal with them - but can't imagine why I would ever include things that I thought might fail.
Malcolm, I don’t think it’s usually a case of “including things you know will fail”, it’s usually more an issue of “saving some money for a less than optimal solution”.
I have a project right now where I can save several thousand dollars (maybe 3-4% of the project cost) by using smaller gauge wire. The tradeoff is more volt drop on the long cable run, so less efficiency in the system. Either way meets code, but the cheaper way has about 5% volt drop instead of the slightly less than 3% of the heavier wire. I can guess which option my customer will pick if I give them the choice, since I think they’ll want to cheap out. All I can do is recommend against it and make sure they sign off on the design.
Bill
Bill,
Maybe "know will fail" is putting it the wrong way. Perhaps better would be "might fail", which to me is still not a good approach to building. If something happens to a house I build, I can accept it if it was a component I had no control over that failed, or an honest mistake I made. What I couldn't accept is thinking "Yeah I knew there was a chance that would happen".
And I see that in the posts here a lot. The questions are often variations on "Can I get away with this?". Which to me is a bad way to make decisions about a building.
Be vigilant, walk around and watch them. If you see them moving in, vacate them. They'll learn.