I am chair of trustees at a fairly lage church in suburban Kansas City. Our sanctuary (120X40ft) was built in the early 60’s and about 3 inches of insulation was installed at that time. I now want to add 12 inches of celluose insulation. Do we need a vapor barrier laid over the existing before adding the new? Think we have adequate vents at each end of the roof.
Al
Replies
Do we need a vapor barrier laid over the existing before adding the new?
No.
Think we have adequate vents at each end of the roof.
Probably don't. We've been increasing the amount of venting significant;ly since those days. Best thing to do, though, is access how it's performed over the years and gop from there. (A good source for such an accessment would be an experienced home inspector - we look at a lot of attics and know what's going on in our areas.
Instead of guessing, here is how to figure if your ventilation is adequate, at least according to current code:
Take your building square footage and square it and multiply it by 144inch squared and divide by 300. That will give you how many square inches of venting you need. On a plan I am building now it equates to 884 square feet needing 46 lineal feet of eave vents and four roof jacks. The formula says it needs 424 sq. inches, and the former provides 472 sq. inches.
Formulas are great, I use 'em all of the time.
OTOH, as a home inspector, I have seen that there is no real life corrolation between tha attic venting formulas and what actually happens in attics. Each house/structure is different.
BTW, don't forget that those formulas refer to "free vent space." The louvers and or screeening in vents reduces the nominal vent space significantly. Some vent manufacturers mark a free vent space measure on their vents.
You're right Bob, a lot can affect the effectiveness of ventilation. Using the minimum standards isn't good enough, in my opinion, but at least it gives people an idea of where to start. Crawl space ventilation is the same. To say that there is no corrolation at all is a ridiculous statement though. I suppose you advocate that full engineering be done on every structure to make sure it's vented properly for it's location?!?
You're right about the screen affecting the ventilation sq" number, and you're probably the first home inspector that I've ever heard of that knows that.
We perform home inspections also, not pest though. I am amazed at how un-knowledgeable the vast majority of home inspectors out there are, it doesn't matter what certfication these guys have. People need to read the wording of their contracts, most don't realize that they may not have any easy remedy of recourse if one of these bozo's really screws up.
Using the minimum standards isn't good enough, in my opinion, but at least it gives people an idea of where to start. Crawl space ventilation is the same. To say that there is no corrolation at all is a ridiculous statement though. I suppose you advocate that full engineering be done on every structure to make sure it's vented properly for it's location?!?
I recommend going with what works in the local area. Start with the formula for new construction, at a minimum.
OTOH, just because an attic doean't meet the formula doesn't mean it's screwed up. I see a lot of attics that don't come close with no signs of excessive moisture.
You're right about the screen affecting the ventilation sq" number, and you're probably the first home inspector that I've ever heard of that knows that.
We perform home inspections also, not pest though. I am amazed at how un-knowledgeable the vast majority of home inspectors out there are,
The one's I know are fairly knowledgable, but I mainly know ASHI members
it doesn't matter what certfication these guys have. People need to read the wording of their contracts, most don't realize that they may not have any easy remedy of recourse if one of these bozo's really screws up.
There is a deeper issue here. For various reasons, the time available for home inspections is pretty limited; much over 3-4 hours and lots of people getting upset. Plus, the prevailing price oif home inspections also limits the time one can spend.
Pay me by the hour and let me inspect until I'm satisfied, and I'll be happy to remove the limitation of liability in my contract.
FWIW, I offer 2 levels of inspection: "standard," with a limitation on liability, and "deluxe" with no limitatiuon on liability but higher fees to cover the additional time necessary. Out of 1800+/- inspections, not one person has chosen the deluxe!
And, of course, there are some bozo inspectors out there. And some of them seem to be teaching some contracctors and sub-contractors! {G}
I've seen too often what happens when an unsuspecting couple or homebuyer puts too much stock in what an inspector has told them about a structure, only to later find out that serious deficiences existed.
I'm not sure that the criteria of the ASHI makes someone necessarily qualified. I may be wrong, but I've always thought that if someone knew enough about residential structures that they would be building them, or doing something other than inspecting them.
We inspect residential as well as commercial, and quite a bit for the federal goverment. We don't let prevailing charges change what we charge. Real expertise isn't expensive, with something of this nature it is invaluable. When something is beyond our scope we'll involve an engineer and get their stamp on any remedies. That is in contrast to what we've seen happen with some inspectors, who seem afraid to admit that they don't know something. Somebody that really knows the systems of a house, and knows them well, has been around long enough and has enough education that they probably won't settle for making what they can get charging what everyone else does for doing home inspections.
Our reputation gets us the inspection work that we do perform. If someone doesn't want to pay the price, they have other alternatives. We feel that we need to dictate how long an appropriate inspection should take, and we do require the person(s) ordering the inspection to be present. We don't care if they don't like spending the time, but most are referred by people that have already educated them as to the difference, or have utilized our services before.
I realize that there are many competent inspectors out there that provide a good service. I certainly haven't run in to many of them though.
I've seen too often what happens when an unsuspecting couple or homebuyer puts too much stock in what an inspector has told them about a structure, only to later find out that serious deficiences existed.
Me too, and it isn't pretty. The inspection biz (like many areas involved in construction in one way or another) has too many hacks
I'm not sure that the criteria of the ASHI makes someone necessarily qualified.
I'm not saying every ASHI member is necessarily qualified, but there are a couple of tests and reviews of one's written reports, and a decent assoc. mag and fairly active forum and continuing ed requirement.
I may be wrong, but I've always thought that if someone knew enough about residential structures that they would be building them, or doing something other than inspecting them.
Similar knowledge base, different skill sets. Plus, more consistent income as an HI for me.
I am not particularly strong in managing large complex projects over a period of time, and would probably be a spectacular failure as a builder. I was moderately successful doing repairs and restorations and the like, but am even better at the mind set and skills needed for inspections.
We inspect residential as well as commercial, and quite a bit for the federal goverment. We don't let prevailing charges change what we charge. Real expertise isn't expensive, with something of this nature it is invaluable.
Congradulations, you've apparently done a great job in positioning your services.
When something is beyond our scope we'll involve an engineer and get their stamp on any remedies. That is in contrast to what we've seen happen with some inspectors, who seem afraid to admit that they don't know something.
The inspectors I know and respect take the same view.
Somebody that really knows the systems of a house, and knows them well, has been around long enough and has enough education that they probably won't settle for making what they can get charging what everyone else does for doing home inspections.
It's not just about money. I made a heck of a lot more during the period when I practiced law. But, most days I dragged myself out of bed, forcing myself to face another day. Now, I make decent money and rarely resnt facing a new day.
Our reputation gets us the inspection work that we do perform. If someone doesn't want to pay the price, they have other alternatives. We feel that we need to dictate how long an appropriate inspection should take, and we do require the person(s) ordering the inspection to be present. We don't care if they don't like spending the time, but most are referred by people that have already educated them as to the difference, or have utilized our services before.
That's terrific. I feel glad for you, and a bit envious. I'm currently wortking on a biz plan to try to transition into that approach. (FWIW, my advisors all say I'm crazy, and that the market I'm in won't support such an approach. One shouldn't let that sortof advice dictate onje'sife, but the last time I defied advisors along such lines I lost my shirt!
I realize that there are many competent inspectors out there that provide a good service. I certainly haven't run in to many of them though.
What all do you do? I get the impression that inspecting ios a side line for you.
Edited 8/16/2002 9:53:21 PM ET by Bob Walker
Bob, you're one of a growning number of people that I've heard about leaving law and going into some type of building related vocation. If you can pass the bar you obviously have the intelligence to tackle whatever else you set your mind to.
And you're right, it's not just about money, and that was a bad assumption on my part. And I would agree that the ASHI inspectors are probably as a whole more reliable than some of the free lancers with no affiliation. And it isn't just home inspectors, it's way too easy to become a contractor in most states too. I wish there was more stringent regulation and competency requirements for both. I'm not in to goverment controls,quite the opposite, but our industry needs something to protect the public.
Inspections are only something that we do by request, and we don't market it much. We are a general contractor. We've gotten to where we are by using old fashioned values. We do what we say we're going to do, when we say we're going to do it. We deliver customer service that is second to none. We've developed relationships with real estate professionals that are comfortable telling referrals that they don't need to get another bid, that we're the company to go with for a variety of reasons. For those that we do business with there are no emergencies that we won't handle, no matter what time it is. We strive to make it a situation where people know they can call us, and rely on us. We try to make their lives easier. Cost becomes less of a factor when you're making peoples lives easier, and they trust what you say and do. People can shop price alone, but if you're offering something better than the rest of the pack you will always stand out.
I personally meet everyone that buys one of our spec homes. I don't like the impersonal, "everything is handled by the escrow agent" approach. I want them to know that we're different, and make sure they've read through the book that comes with their home about how their home is different. I think it's the right way to treat people, and it's the best marketing we do.
We are never arrogant, but if someone isn't willing to pay the price, then we will offer other solutions and part friendly. Those that refer us for inspection work let people know that we won't be the cheapest up front, but the value is there. We look at a lot of investment properties, and at least those are somewhat less emotional than regular residential.
Don't let the naysayers say that you can't set yourself apart, I don't believe it's true in any market. If you do things better than everyone else, and deliver a product that is superior, over time you are a field of one.
I truly believe that successful people are successful because they do the things that unsuccessful people won't, or don't. Huge metro area or small town, you can stand out if you want to.
Sounds like you've put together a gret business!
Where abouts are you located? (With a moniker like "beach bum" I'm guessing it isan't the mid west{G}!)
Hi Bob, we do work in Washington, Oregon and Alaska. Until a year ago we were headquartered out of Portland, Oregon. I've spent most of my life in Alaska, and the Portland area was starting to feel really congested. There is a lot of great work there, but having two young kids my wife and I decided to move ourselves to the Washington coast. After building houses for years in interior Alaska, meeting the new environmental challenges here on the coast is a lot of fun.
One of my best friends is an attorney that wishes he could do like you've done and go another direction. He's been at it 15 years as a defense attorney though and can't seem to get away from it. He doesn't find it rewarding though. He has handled some big cases and been on Larry King and Good Morning America and all of those types of programs, and his ego seems to like that okay.
We built a home in St. Helens Oregon four ourselves, and it was this attorney friend and his wife that ended up buying it. The joke now is that they'll end up eventually moving here to the coast too.
What part of the country are you in? You've done a lot of inspections, so you've obviously marketed yourself well. What type of law did you practice prior to giving that up? I'll bet you're one of the few inspectors that has the capacity to actually undertand their own contract.
Have an enjoyable weekend.
You folks all had alot of fun calculating vent areas and stuff but forgot the customer needs. Do they need more roof venting?
Is there a problem now? If the roof is wet, call someone who knows what the hell they are doing. You want to find someone who will air-seal the top of your building. If they start telling you about roof venting, fake a medical emergency and ask them to leave immediately.
If the roof is dry, leave the sawzalls on the truck.
There it is in a nutshell.
-Rob
Rob, you are obviously just an obnoxious moron. I'm afraid that the roof being wet might only mean that it is raining. However, if there is moisture in the attic area, then there might be a problem.
And it isn't what the customer needs, it doesn't matter who is living in the house. The need for ventilation is dictated by many factors, but as mentioned, the required minimums are at least a place to start.
I have built several hundred homes and have not had any problems with moisture. Many of those homes were in the interior of Alaska where vapor barrier problems and moisture are a common occurence.
You don't sound like the type of person anyone should call unless they need a 2x4 or something moved from the driveway to the dump.
rob.. where do you want me to send the sawbuck ?Mike Smith Rhode Island : Design / Build / Repair / Restore
"........where do you want me to send the sawbuck ?"
Hell, you can send it to me. I like those things, but they're hard to find. I only know of one guy in this area that still has one that works.
My identity lies in not knowing who I am
Don't add a vapor barrier above the existing insulation.
IMO adequate attic ventilation and blown in insulation don't mix. A breeze up there moves the insulation usually blocking vents, then the sparse spots let heat through causing ice dams in the winter. I personally like an insulation that stays where I put it.
IMO adequate attic ventilation and blown in insulation don't mix. A breeze up there moves the insulation usually blocking vents
FWIW, in my area (NW Ohio - where we get some fair breezes out on that flat, treeless, countryside) it is very unusual for insulation to be displaced from air movement in the attics; out of 1800 or so attics, probably with 2/3 - 3/4 blown cell or FG, I've only seen one where the insulation had been moved around by wind.
Other areas may have different results.
You maybe correct. It might not be the wind but bad installers. Seen to many attics with plenty of vents on the outside but when you get in them you need a flashlight in the middle of the day. No light through the vent guaranteed no air.
And what are you doing in 1800 attics??????????
Edited 8/15/2002 9:31:23 PM ET by GEOB21
That's what Tyvek is for.
IMO adequate attic ventilation and blown in insulation don't mix.
Well then, at least 95% of the homes around here wouldn't meet your criteria.
You did not say what your roof construction is, but I'll assume it is trussed. Next question is raised heel or common trusses? What kind of soffit over hang, 12, 16, 24,...inches? What kind of vents are in the soffit. How large are the gable vents if that is what you have? Lots of question need to be asked and answered to give you any recomendations. Do a search here on roof /attic ventilation and you will find lots of discussions in the archives(the old forum would have had some real barn burners).
I have to agree with Bob. I don't live in as windy an area as he, but as a remodeler, I have seen a lot of attics. It is rare that I ever see loose insulation blown far enough away from the wall top plate to cause significant enough heat lose for ice damming to occur. When I run into that problem it is generally from inadequate insulation and venting.
I also agree that no vapor barrier should be used above the existing insulation. If there is not one below it now, adding one on top will create a ton of problems because it would be on the wrong side.
Blown insulation on top of blown insulation is fine up to the point that the additional weight could cause the ceiling drywall to sag. This can occur with cellulose. Blown f/g does not present this type of problem, but is not as effective as cellulose at the the same thickness. Unfaced f/g rolled across the lower truss cords reduces the load on the drywall in the joist bays. Roll fiber glass can be purchased that is denser than blown f/g for a given thickness.
If you have not experienced ice damming in the past, the addtional insulation probably won't cause it to occur either. Just make sure you don't block any existing vents with whichever type you use. If this is a church DIY project, at least hire a good insulation contractor as a consultant. If you are contracting the work , you know the drill... referances, BBB, bonding, insurance, etc.
Best of luck
Dvae
No need to add the vapor barrier. It's arguable whether it would be a good or bad idea in the general case, and for a church (with relatively low internal moisture generation) it's fairly certain to be unnecessary.
If you only have vents at each end of a 120 foot roof that's certainly not an ideal situation, but the primary issue would be ice damming, and if you haven't had the problem so far then it wouldn't occur with more insulation.
Uh, zegarac -- you need to repost your question with a different subject or append it here. You've gotten torpedoed by the similar thread title bug.