Ask the Ex­pert

You may have heard of SIPs (struc­tural in­su­lated pan­els) in re­gard to tim­ber home con­struc­tion, but how can they ben­e­fit log homes? We went straight to the source to find the an­swers.

Log Home Living - - CONTENTS -

SIPs in Log Homes

all the things your log home should be — sturdy, se­cluded, com­fort­ably fur­nished — there’s one item that should never make the list: cold. First and fore­most, your log home is a shel­ter built to save you from be­ing rav­aged by the el­e­ments. In a ful­l­log home, your solid walls pro­vide their own built-in pro­tec­tion, but your roof — and any con­ven­tion­ally framed ar­eas your home may have — will re­quire some re­in­force­ments. Sure, you can turn to fiber­glass batts or even spray foam, but we wanted to learn more about a third op­tion, struc­tural in­su­lated pan­els, or SIPs. We sat down with Stephen Munn, gen­eral man­ager of In­sulspan, a lead­ing SIPs man­u­fac­turer, to learn how these su­per-in­su­lated pan­els can en­hance log home con­struc­tion.

LHL: First and fore­most, how do SIPs work?

SM: SIPs are cre­ated by lam­i­nat­ing two pieces of per­for­mance-rated OSB2 (rated for struc­tural ap­pli­ca­tions) around a con­tin­u­ous core of EPS (ex­panded poly­styrene) foam in­su­la­tion. We can pro­vide panel sizes as large as 8-by-24 feet, which al­lows us to cover a large area with one panel and re­duces the num­ber of studs needed for con­struc­tion. This also re­duces heat loss, ther­mal bridg­ing and air leak­age. The other key

thing that we do with SIPs is we use a sealant at each of the joints, which di­min­ishes the air flow. You can’t re­ally do that with fiber­glass batts or blown-in in­su­la­tion.

How do SIPs com­pare with other types of in­su­la­tion? What ad­van­tages do they have over the al­ter­na­tives?

Batt in­su­la­tion has an R-value of 8.8 but with SIPs we can get an ef­fec­tive R-value of around 22.6. A big fac­tor in this is the amount of lum­ber that goes into cre­at­ing the wall or roof. Be­cause of the struc­tural as­pect of the SIPs, not as much lum­ber is re­quired. Lum­ber doesn’t have the same ther­mal re­sis­tance as the SIPs.

In re­gard to spray foam in­su­la­tion, one of the ad­van­tages is we can man­u­fac­ture SIPs as thick as 12.25 inches, which of­fers an R-value up to 45. If you re­ally want to in­crease the R-value, you can add an­other 20 per­cent by us­ing a graphite-en­hanced EPS foam. You can’t get a spray foam that’s that thick and pro­vides that high of an R-value. The thing is, spray foam is cre­ated us­ing a chem­i­cal re­ac­tion that will off-gas and break down over time, re­duc­ing the R-value. The EPS is a rigid, closed-cell foam made of plas­tic and air, which doesn’t de­grade.

For the lay­man, what is an R-value?

The R-value is the ther­mal re­sis­tance to the trans­fer of heat. It’s what’s used to mea­sure the ther­mal re­sis­tance of a prod­uct. The higher the R-value, the greater the abil­ity a ma­te­rial has to re­sist the trans­fer of heat in or out of the build­ing.

How much en­ergy can be saved by us­ing SIPs over a con­ven­tional batt in­su­la­tion?

The amount of en­ergy saved would de­pend on the size of the build­ing. With a 2-by-6 stud wall with R-20 batt in­su­la­tion, the ef­fec­tive R-value is around 16.8, and with a 6.5-inch thick SIP we get an ef­fec­tive R-value of ap­prox­i­mately 22.6. But it re­ally de­pends on the size of the struc­ture and the thick­ness of the walls or roof sur­faces that you’re us­ing.

SIPs are com­mon in tim­ber home con­struc­tion; how do you use them in a log home?

With log homes, they’re re­ally ef­fi­cient as a roof ap­pli­ca­tion. If you’re work­ing with a log home that’s a hy­brid, such as with log ac­cents as op­posed to gen­uine, full-log walls, SIPs mesh very well with that type of con­struc­tion.

How much do SIPs cost in re­la­tion to other prod­ucts, es­pe­cially in terms of ROI?

SIPs have a slightly higher ini­tial-in­vest­ment cost, but when you fac­tor in the speed of con­struc­tion and only need­ing to have one trade con­trac­tor as op­posed to two (fram­ing and in­su­la­tion), buy­ers ac­tu­ally can save money dur­ing the in­stal­la­tion process. The real sav­ings, how­ever, is what own­ers will see over the life of the home. With SIPs, the house re­quires a smaller HVAC unit be­cause of the higher R-value and the re­duced air flow, so equip­ment costs less. Then you’ll save even more on en­ergy costs over time due to fewer air ex­changes. These are the long-term sav­ings.

What tech­no­log­i­cal ad­vances have been made in SIPs over the years?

The ad­di­tion of the graphite en­hanced EPS has en­abled us to in­crease the R-value within all panel sizes. For ease of con­struc­tion, we base our SIPs off stan­dard lum­ber sizes; so, as an ex­am­ple, in a 6.5-inch wall, we can in­crease the R-value by 20 per­cent with­out in­creas­ing the thick­ness. In­sulspan pro­vides a com­pre­hen­sive, ready-to-as­sem­ble pack­age, where we in­stall as much lum­ber as pos­si­ble, so all the win­dows and doors are framed out ahead of time in the fac­tory. When the pan­els ar­rive at the site, with the con­struc­tion draw­ings we send, it’s lit­er­ally tak­ing part B and at­tach­ing it to part C and nail­ing them to­gether, then you at­tach to part D … it re­ally speeds up the con­struc­tion process. We also have the elec­tri­cal chases ac­counted for in the pan­els, mak­ing the wiring in­stal­la­tion quick and easy.

Are SIPs some­thing the av­er­age per­son could learn to in­stall on their own? What sort of train­ing would a do-it-your­selfer re­quire?

We don’t just send out the pan­els and say, “Good luck!” We have in­stal­la­tion guys that ex­plain the process of how to in­stall them. We also have In­sulspanU. Once a quar­ter we bring peo­ple in for a one-day class to go through all the ben­e­fits of SIPs and then pro­vide in­struc­tion on how to in­stall them, in­clud­ing hand­son prac­tice at the end.

There are lay­men who in­stall SIPs when they choose to. Most peo­ple don’t have the time or the in­cli­na­tion, but there are quite a few home­own­ers who do it them­selves.

SIPs are a high-per­form­ing, en­ergy-sav­ing op­tion for roof ap­pli­ca­tions in full-log homes.

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