i don't think you should or need to block it. i've never heard of a house being uprooted from concrete piers and i grew up in puerto rico with hurricanes.

peggy,
if you have concerns the best thing you can do is to hire a structural engineer to come take a look at your house and the anchoring systems. It would cost some $$ but if you are worried than piece of mind may be worth the money spent.

also,
who inspected your house when you purchased. If it was a typical 'home inspector' then they might not be qualified to make an accurate judgement on structure. and would just be able to give you a general overview on what they observed. (where as an engineer would be able to calculate the forces)

hope this helps

Javier and cln1: Thanks for replying. By way of additional info, the house is on 12 x 12 wooden piers and thru-bolted. Entire house is built with 2 x 6's instead of 2 x 4's--walls are 6 inches thick -- and we have a hip style roof.

I am not so much concerned about house blowing away as I am with making sure that I do the maximum possible to minimize our risks. I just don't know the physical dynamics of leaving the crawlspace open as opposed to closing it off during hurricanes. During Hurricanes Charlie and Wilma, we could feel the wind under the house, but it never felt like it would uproot the house.

I think I will take the suggestion of speaking with an engineer.

Thanks
Peggy

Don't close off the crawlspace as a means of hurricane protection. Adding plywood will increase the area of the building catching wind and therefore increase the load the structure will be required to withstand.

ahhh something up our alley Javier

ok couple questions before offering any sort of diagnosis

1. what is the angle of the hip roof
2. what direction was the wind blowing when it passed over your house
3. have the bolts to the piers been checked post hurricanes
4. what type of bolts/bolting system was used
5. do you have shutters on the windows and were they closed during

Note that whilst we are a aware of the damage forward winds cause we must also be conscious of the return current or Edi. This is the torent that is created as wind passes over an object and is a negative current or suction. Many things affect this current namely pitch and pressure. Whilst it is possible to "engineer" the effects of Edi currents by the structural securing of members some of the best advice is to allow the wind to run its course, which seems to be a possible case with your sub floor. Because the air was able to pass through the space it reduced the pressured that would of been applied to the walls and roof of your house. I would second cln1 recommendation of getting a structural engineer, however I would be keen to procure one with practical knowledge/experience of mitigated hurricane design.

yes... i'd agree w/ el jeffe. i'd think that "blocking" off the crawlspace will only increase the forces acting on the structure while adding nothing to the anchoring the piers provide.

if you want to make your house more resilient, you'd have to structurally reinforce what you have already. plywood won't do any of that. architechnophilia has addressed some of the possibilities.

Thanks all!! I sure appreciate the responses. Angle of the hip roof is 7/12 (we think). There is a overhang on all four sides of home of about 2 feet. The underside of the overhang is enclosed with plywood, then covered over with the soffitt and fascia. Incidentially, when our house was reroofed two years ago with tin, the tin was put on over the old roof -- which was still in pretty good shape. The reroof was done for aesthetics.

The winds during Charlie came almost directly out of the South for most of the hurricane. The winds from Wilma came almost directly out of the North -- and the backside was stronger than the front side.

Underneaith the house, the piers are each thru bolted with four 1/2 bolts, think there are piers about 6 foot on center under entire structure -- house is small at 38 x 38. Underside was inspected post hurricane and no apparent changes were seen.

We put 3/4 inch plywood over the windows during two of the hurricanes -- Charlie and Wilma. We got so many in Florida the last two years, I cannot remember which of the other ones gave us a pretty good blow!

So, I think you've made me feel pretty safe now with foregoing plywood for the crawlspace, but I'm curious what those answers add to the equation.

Now my only downside is that there is no interior room in my house. Anyone know how well those preformed tub/showers have held up during hurricanes? LOL

Many thanks again!
Peggy