Island town building inspectors are bracing for a run of new building permits over the next three months in advance of a new state building code regulation which could raise building costs on average by five per cent and as much as 10 per cent.

The news comes as renovation and addition permits have driven the Island construction business this year. Renovation and addition permits ranged from 64 to 90 per cent of total permits issued, depending on the town.

According to one Edgartown town building official, “the key change [in the new code] is a requirement for high-impact ‘hurricane’ windows which quality window vendors tell us will add 40-60 per cent to window costs.”

Windows are typically from two to 11 per cent of total construction costs, depending on home design, estimated Colin Whyte of Martha’s Vineyard Construction Co.

Conversations with other builders in the middle-price range indicated that window costs are five to six per cent of total costs. The impact on an $800,000 house would be $20,000 under the current code levels.

West Tisbury building inspector Ernest P. Mendenhall is already seeing a permit request bubble and expects it to continue through the fall.

“When we talk several months from now, I believe we’ll be discussing the level of increases [in building permits],” he said.

Through August, West Tisbury had issued 103 permits compared with 115 in prior year. Thirteen of the permits were for new builds in 2007 compared with 15 in 2006.

In fact, 90 per cent of permits issued were not for new construction, a trend reflected Islandwide, with permit statistics showing single-home construction to be virtually flat other than in Edgartown.

The action is in renovations, additions, garages and sheds. Seventy-nine per cent of Tisbury permits were for additions and renovations. Tisbury permitted 19 new homes through Sept. 5, compared with 20 through the same 2006 period and issued 78 permits for additions and renovations in 2007 compared with 79 in 2006.

Edgartown has the largest percentage increase in new building permits issued year to date with 61 permits compared with 39 issued in 2006 through August. Addition and renovation permits from Edgartown were not available at press time.

In addition to a 64 per cent increase in single-family-home permits, the Edgartown increase may be related to a beat-the-clock move by homeowners and their builders for both new homes and renovations.

In Edgartown, the bubble may have already occurred with the spate of new permits. Ursula Prada, assistant to building inspector, has not seen or felt urgency in conversations with builders and homeowners.

“That doesn’t mean they aren’t being busy [creating permit filings], we just haven’t seen it yet,” she noted.

Chilmark new builds were flat at 12 permits, the maximum number of new houses allowed by the town. Oak Bluffs has recorded six new construction permits, down one from 2006.

Ramifications of the proposed new state building window code are several.

First, the Massachusetts building division on Wednesday extended the start date of the new codes from Oct. 1 to Jan. 1 while it wrestles with the new regulations. State officials reportedly are pondering whether or not to reduce the standard for high-impact glass required, from ability to withstand hurricane wind speeds to lower wind speeds.

Should that occur, the impact on construction costs would be cut in half. “Window costs would increase only 20 to 40 rather than 40 to 60 per cent,” one building official said wryly.

One builder/remodeler was sanguine about the new regulations, noting that he now installs windows that surpass code and he was hopeful that the cost increases would be mitigated or eliminated as a result.

Next, how will the increased window costs affect architectural design and the addition/renovation market, typically beginning in the $100,000 price range?

Builders and remodelers report strong business in that category. The theory, builders say, is that flat real estate prices lead owners to look at upgrading their existing home, even to adding elaborate tree houses.