Blinds, Shades and Shutters - Vertical blind, OK to hang on drywall?

I notice above my patio door, the header does not come out just behind the drywall, but a little (1-2") behind. So it is block-air/insulation-drywall.

I am planning to put fauxwood vertical blind on it. Those fauxwoods are a lot heavier than vinyl, and a LOT heavier than fabric. I am not sure how heavy exactly they are (anybody would like to give an estimate? 78"W x 97"H). I am guessing they are 60lb. This, together with the force when I pull to open or tilt, and when the blind is stacked to the side, could mean there may be perhaps 60-70 lb on the side bracket (guesstimate).

My question is, what is the best way to hang it? Using a drywall anchor, or use a really long screw. I am not sure how strong, realistically, those anchors are (reading the loading number on the box, I think it may be a little optimistic). If I use a long screw without an anchor, assuming I hit the block behind the wall, does that create pressure on the drywall, as there is only air (or insulation) between the two.

Any idea will be appreciated.

Regards,

Kawah

There have to be firring strips behind the drywall. Check around with a studfinder.

I've seen that situation before. You should find a stud at each end of the door. The other 1 or 2 brackets can be screwed in to molly bolts or toggle bolts. Dont use a long screw into the header since the pressure will collaspe the sheetrock. The control end of the blind is critical and you should be into a stud there. The others will support the weight.

Thanks for the info. I think they have a piece of wood approx 1" above the trim (this is as far as I can tell with a stud finder):

-------------------------------
Wood
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Trim
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I also found the curtain blocks at both ends. Again, I appreciate all the info thus far. Especially it has been suggested to me using a long screw to go in the block. Now with Johnam's reply, I don't think I would do that. Also did some "back of the envelope" calculation, from blind sample, that the total weight would be about 50lb, and each bracket will need to hold 50-60lb (assume 3 brackets, as the mounting bracket is a lever). That means each screw may need to hold 30-40lb. Would a molly bolt (or an anchor bolt) be enough?

Again, appreciate the helps,

Kawah

I think a molly bolt should work but a toggle actual is supposed to have greater holding strength.