Few un­der­stand ad­e­quate at­tic ven­ti­la­tion

Winnipeg Free Press - Section G - - HOMES - ARI MARANTZ

QI would ap­pre­ci­ate your opin­ion and ad­vice in the fol­low­ing mat­ter. We have a home built in 1964. The sof­fits, fas­cia and eave­stroughs were up­graded to alu­minum in 1997. The fas­cia and sof­fits were of a colour that re­stricted our choice of stain colours, and it was sug­gested to us to have them painted, thereby al­low­ing for a stain colour that would com­ple­ment the sof­fit and fas­cia. The painter did a good job, but now the small vent holes are com­pletely or par­tially blocked with paint. I es­ti­mate only 10 per cent of the pre­vi­ous vent­ing ca­pac­ity is avail­able. We did not an­tic­i­pate this. My ques­tion is re­lated to ven­ti­la­tion re­quire­ments. There are ex­ist­ing gable vents and roof vents, ac­cord­ing to the rec­om­mended ra­tio. But how do I de­ter­mine whether there is suf­fi­cient sof­fit vent­ing to en­able ad­e­quate cross-ven­ti­la­tion and air cir­cu­la­tion? If the vent­ing is in­suf­fi­cient, would adding more roof vents or sof­fit vents work, or do I have to com­pletely re­place the sof­fits? Thank you.

— Dave AN­SWER: The need for ad­e­quate ven­ti­la­tion from sof­fit vents on a tra­di­tion­ally in­su­lated at­tic is of­ten mis­un­der­stood, and your ques­tion ad­dresses that need well. ‘Look for dark stains, frost, wet spots or other in­di­ca­tions there

is a mois­ture prob­lem’ In­creas­ing the amount of at­tic ven­ti­la­tion in this area should be the goal af­ter ren­o­va­tions. While it may seem odd, on nu­mer­ous oc­ca­sions I have seen homes that have re­duced at­tic ven­ti­la­tion from the sof­fits af­ter ren­o­va­tions or up­grades. Most of the time this is be­cause of im­proper in­stal­la­tion of blown-in fi­bre­glass in­su­la­tion, which may touch the roof sheath­ing around the perime­ter of the at­tic. This ma­te­rial is nor­mally fluffy and not very re­stric­tive to air, but can ex­hibit the op­po­site prop­er­ties in this lo­ca­tion. Be­cause the in­su­la­tion is more com­pressed in this area and may be sub­ject to wet­ting from melted at­tic frost, it can re­strict proper air move­ment in the at­tic caused by nor­mal con­vec­tion. Be­cause older at­tics are not de­signed for that high a level of in­su­la­tion near the eaves, try­ing to achieve mod­ern in­su­la­tion lev­els can be prob­lem­atic. Paint­ing over ex­ist­ing sof­fit vents can have a sim­i­lar re­sult. The first thing you must do to de­ter­mine what, if any­thing, needs to be done to your newly painted sof­fits is to look in the at­tic. By care­fully re­mov­ing the at­tic hatch and view­ing the at­tic from a lad­der, you should be able to get a good idea of the con­di­tion of the at­tic and in­su­la­tion. A pow­er­ful flash­light or por­ta­ble trou­ble light may be re­quired so the un­der­side of the roof sheath­ing can be viewed. Look for dark stains, frost, wet spots or other in­di­ca­tions there is a mois­ture prob­lem in this space. Th­ese stains may be on the fram­ing or sheath­ing and may be ac­com­pa­nied by vis­i­ble sag­ging of the roof sheath­ing be­tween the rafters. If there are only mod­er­ate stains and no signs of sag­ging or rot­ten sheath­ing, there may be lit­tle to worry about. This time of year, with the very cold tem­per­a­tures, a thick layer of frost on th­ese com­po­nents will also be a sign of trou­ble. Should you see any or all of th­ese warn­ing signs, the next step is to de­ter­mine if the in­su­la­tion around the perime­ter is too re­stric­tive. You should be able to see a no­tice­able space, a min­i­mum of three to five cen­time­tres, be­tween the top of the in­su­la­tion and the roof sheath­ing. If this is present and you can see all the way down to the eaves, im­prov­ing sof­fit ven­ti­la­tion may not be needed, or can be done fairly eas­ily. It the lo­ca­tion of the at­tic hatch does not al­low a good view of th­ese ar­eas, turn off your flash­light once you have poked your up­per torso into the hatch. On a sunny day, you should see small bands of light at the eaves, and from the roof and gable vents as well, that tells you ad­e­quate air­flow is likely. If it is com­pletely dark around the perime­ter of the en­tire at­tic, more ven­ti­la­tion is prob­a­bly re­quired. You have iden­ti­fied a few pos­si­ble ways to re­store ad­e­quate at­tic ven­ti­la­tion be­cause of the plugged sof­fit vents, but only one or two may be cost­ef­fec­tive. While I un­der­stand the cos­metic rea­son for paint­ing your metal sof­fits, that was a poorly thought-out mod­i­fi­ca­tion. One of the big­gest benefits of pre-fin­ished alu­minum sof­fits is the lack of main­te­nance re­quired. Now that you have painted them, you may have to redo the job at some point, es­pe­cially if mois­ture leaks out of the sof­fits be­cause of spring frost melt­ing in the at­tic, which may cause the new paint to peel. One of the big­gest benefits of pre-fin­ished alu­minum sof­fits is the lack of main­te­nance re­quired If this hap­pens — a sure sign at­tic ven­ti­la­tion is in­ad­e­quate — the so­lu­tion may be to com­pletely re­place them. Bar­ring that catas­tro­phe, adding more vents in this area and the roof peak may bring things back to an ac­cept­able level. While it may not have the best vis­i­ble ap­peal, it is pos­si­ble to in­stall small sof­fit vents di­rectly over the metal sof­fits. Th­ese are avail­able in nat­u­ral alu­minum fin­ish or pre­painted in var­i­ous colours. For your pur­poses, you could even hand-paint them to match the ex­ist­ing new sof­fit fin­ish, tak­ing care not to fill the vent open­ings with ex­cess ma­te­rial, like the painter did on your home. The ex­ist­ing metal sof­fits can then be cut in sev­eral ar­eas, slightly smaller than the new vents, which can be screwed in di­rectly over top. The ben­e­fit of this method is not only the min­i­mal cost, but the abil­ity to cut or drill ad­di­tional holes in the older ply­wood sof­fits be­neath the metal ones, in­creas­ing air­flow rather than re­strict­ing it. Paint­ing your pre-painted metal sof­fits to im­prove the aes­thetic ap­pear­ance of your home may have been a way to achieve that goal, but now may re­quire more work sim­ply to re­store ad­e­quate at­tic ven­ti­la­tion. Vis­ually in­spect­ing your at­tic should tell you whether this is nec­es­sary, of whether the blocked vents have had min­i­mal ef­fect on the over­all con­di­tion of your at­tic. Ari Marantz is the owner of Trained Eye Home In­spec­tion Ltd. and the past pres­i­dent of the Canadian As­so­ci­a­tion of Home & Prop­erty In­spec­tors — Man­i­toba. He can be reached at trained­eye@ in­ame.com or 204-291-5358. Check out

his web­site at trained­eye.ca.

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