I'm tearing off my nasty aluminum siding down to the original tongue-and-groove dutchlap-type wood siding. The original wood siding is generally in pretty good condition, but there are a few places where there are some holes, cracks and gaps--mostly around the area where someone once put new windows in. I've taken those (large) windows out and framed for new, smaller windows. I patched in new sheathing to cover the old window space. I'm going to wrap the entire house in Tyvek or another similar housewrap. How important is it to seal those cracks and gaps under the housewrap? Say I didn't do anything with them... won't the housewrap (properly applied and taped) block air infiltration through those openings? And from an insulation viewpoint, isn't the insulating benefit of sealing those openings minimal (not much better than the wood siding itself)? Don't get me wrong... I'm not saying that I'm planning on doing nothing with these openings--I will fill them, but I want to know how diligent I need to be, considering that I'll be using a housewrap. I don't need to go to the level of filling the nail holes from the aluminum siding, do I? Your comments and suggestions are appreciated. Please be kind to me--often when I ask these types of questions (not always in this forum) I get blasted by somebody who thinks I'm trying to cut corners or half-a$$ a project. I assure you I'm not. Thanks, Brian

I am replacing some siding on a wood frame house with board (actually plywood) and batten siding. The lining between the siding and insulation is black and kind of papery and fibrous - not sure what it is. I need to replace a small area of this material. I have heard about House Wrap and some other product made of Tyvek, but because most houses in south Florida are concrete block, most stores don't carry it. I did find a huge roll at one Lowe's, $150. I only need a few square feet. Any suggestions for a substitute material? Apparently it has to be breathable but waterproof. Thanks!