Is Tyvek moisture barrier necessary in Austin, Texas?
cGZesTHnKf
| Posted in Energy Efficiency and Durability on
My husband and I are building our first home and want to know if the Tyvek moisture barrier our builder offers as and upgrade is necessary in our climate.
We live in Austin, TX. In our research so far we have found that it is used more often than not, but we aren’t sure if that is a correct assumption. It costs about $2,200 extra, so we don’t want to include it if it’s not actually necessary. However, if it is, we are more than willing to pay for it. Thanks for the help 🙂
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Tonia,
Most building codes require a home to have a water-resistive barrier (WRB) between the siding and the sheathing. This can be asphalt felt, plastic housewrap (for example, Tyvek) or one of several other products. But you must have a WRB of some sort -- it's not optional.
For more information on WRBs, see All About Water-Resistive Barriers.
Tonia
What is the wall assembly your builder is using. Wall thickness, type of insulation, siding or cladding, and WRB (other than Tyvek).
Martin, that article told me everything I needed to know! Thanks!
Is your builder's typical detail vinyl siding over OSB with no WRB unless you pay extra?
David,
I'm not exactly sure how to answer that, as we have only recently decided to build. We just picked up an upgrade v. standard feature list and are currently going through one by one. This one wasn't something we had been able to find a direct answer to on our own. What I think you are asking is what they offer standard if we have to pay extra for tyvek? Or are you asking what siding they plan to use and how it would affect which moisture barrier would be more effective? We are just beginning to understand all of the terms, so thanks for your patience and your response.
Just to clarify, we haven't broken ground yet. We just decided on a floorplan and decided to build instead of purchase resale. We are doing our own research to be as educated about the process as possible before we start building. Thanks!
Tonia,
As Martin pointed out, a Weather Resistant Barrier can be achieved by asphalt felt, plastic "house wraps," or other materials.
What's important isn't the material. What is of major significance is the builder's methods of WRB installation. A good builder will properly flash all wall penetrations (windows, gas lines, exterior outlets, etc), deck ledgers, kick-out flashings, and wall-to-roof intersections. He/she will properly lap all joints, follow the installation guidelines of the WRB manufacturer, and cover up the WRB with the exterior finish as soon as possible (all WRBs have exposure limits).
I know this is probably way too much information, but I think you as a homebuyer can ask the builder a few basic questions to get a feel for his construction practices.
Ask him to reveal his "moisture management" methods. Ask him to see flashing details.
Ask him if he/she uses wall penetration flashings.
Ask how the windows are installed. Are they integrated with the housewrap? Does the builder use panned-sill flashings?
Ask about the use of deck ledger and kick-out flashings.
Look, you really don't need to know what any of these things mean. Write down the questions and ask away. If the builder stumbles for the answers or flat out doesn't know what these materials/methods are, you should find another builder.
Brett, of course she would need to know what all those things mean. Are you suggesting that she could gauge the quality of the house by seeing if the builder stumbles over the answers? The industry is full of salespeople who sell quite capably to buyers who aren't knowledgeable.
Tonia, the fact that the builder typically doesn't include a weather-resistant barrier (Martin called it a water-resistant barrier) is a terrible sign, in my opinion. There are a lot of builders out there who cut every possible corner to keep prices low, and in most cases you won't even know it, in fact a lot of it can't be seen after the house is finished. What you may find, over time, is that you start to have problems with the house that require expensive repairs, reduce the resale value, or both. Specifically, a WRB is a huge part of keeping rain water out of your walls. Without it, there is almost no way that you can expect long-term to avoid problems with water intrusion, although the builder can expect to cash your last check before you start seeing problems.
My suggestion is to find a builder who specifically includes this type of application, along with many others that will make the house durable and energy efficient. Either that, or hire a very qualified home inspector to make progress inspections of your house as it's being built, and don't make payment for anything that hasn't been done correctly. If the builder you're talking to does a lot of houses, you may find an inspector who is already familiar with their work and can give you some insight.
Anyway, the idea of building without a WRB makes me sick. According to the NOAA site, there's plenty of rainfall there in Austin. You might be able to skip the WRB in the Mojave Desert. The only caveat I can think of here is that the builder uses Zipwall or exterior foam with poly z-flashing, but somehow I doubt it.
Tonia,
Since you have not broken ground yet...
I urge you to take advantage of Austin Energy's... Green By Design Workshop
I would post a link...but their website is down at the moment.
The workshop is only offered a few times a year ... but it is not-so-expensive and extremely worthwhile.... book early it fills up fast.
please....Do not "pick out a floorplan" or a builder until you have done more research.
A 9' x 150' roll of Tyvek (1,350 sf) is $150.00 plus tax. A big house might use 2 rolls, $2,200 for the Tyvek option is a ripoff, look for another builder.
Wow! Thanks for the responses. Right now I only have a few moments to scan through, and give a few quick answers. First, the builder does include a WRB, it's just not Tyvek. In fact, Tyvek is the only one that is an upgrade. I'm guessing that is probably why they are charging so much? They might want to encourage buyers to choose one of the other available options (such asphalt felt, etc...) Which led us to question if Tyvek was the best option available, and if not, then what is? Second, we really appreciate all the valuable information everyone has shared. We intend to thouroughly educate ourselves about the process, and have only begun to do so.
This is getting confusing! What WRB is included in the base price? Felt?
Tonia,
The choice of WRB -- for example, Tyvek or asphalt felt -- doesn't matter much. What is much more important are the water-management details and paying attention during installation -- factors such as:
Including a rainscreen drainage gap
Using proper flashing at all penetrations
Lapping the WRB properly at seams and intersections with flashings.
.
Hey Tonia,
I would recommend contacting your local Tyvek rep, Corey Ball. Corey can explain the benefits of the upgrade and provide answers for your questions. Feel free to send him an email at [email protected] or give him a call at 512-944-5899.
[David, some Austin builders use T-Ply as a "standard" option and consider it a WRB. Not sure about this scenario, but I'm sure the home would use more than 2 rolls of HomeWrap and don't forget the cost of labor. The upgrade would provide superior protection compared to what is offered for free. Peace of mind in the long run.]
B Mac,
Why contact a Tyvek rep to learn the benefits of Tyvek? After all, if you contact a Typar rep, he or she will tell you the benefits of Typar, and if you contact an asphalt-felt rep, he or she will tell you the benefits of asphalt felt.
I'm not sure why contacting someone who is paid to promote a product will help a homeowner make this decision.