Cleaning 50 year old rafters before applying foil tape on insulation board

[Bill Dufour]

I am insulating my garage roof with polyiso board in between the 2x4 truss rafters. I plan to use foil tape to seal the seams. It will stick fine to the new insulation. But how can i clean the old rafters so the tape will stick. They are fairly clean not real dusty, no spider webs but touch them and my hands get real dirty real fast.
I am hoping to do it from the ground as much as possible.
Maybe a sponge mop and soap. A roofing tar brush?
Bill D

[Kev Williams]

brush attachment on a good vacuum; Shark, Dyson, etc... no reason to get the wood wet, you just need the loose dirt & dust removed.

[Zachary Hoyt]

I don't know how to do it best from the ground. It seems like what would work best would be something like a rotary broom on a pole, if such a thing exists, or a flap wheel. If you could adapt a flap wheel to an electric pole saw head I think that would work really well, but I don't know how feasible that is. I think that maybe more than cleaning you might want to expose a new surface for the tape to stick the best.

[Mike Soaper]

Strong leaf blower?, if you try it wear a mask. I was told some car detailers use a leaf blower before or instead of a vac.

[Maurice Mcmurry]

I have used contact cement as a primer before applying tape when I want the bond to be as permanent as possible. Have had good results using my Great Stuff Pro foam gun to seal foam board in-between rafters and trusses. The foam can be un-attractive but there are ways to deal with that. I used a stiff bristle gong brush to scrub loose dirt off of the underside of our daughters roof deck and rafters before spraying with Foam-It-Green. None of it is fun work. Good insulation is worth it.

Floor primer for peel and stick tiles might be worth trying.

Henry 1 qt. Floor Primer 12054

[Andrew Hughes]

How about scabbing on a clean batton to the bottom.

[Bill Dufour]

OP here: I bought a sponge mop at the dollar store and slipped a tee shirt sleeve over it. Cut a hole for the handle first. Held on with rubber bands. Worked fine. very little dirt came off. Probably not worth the effort.
Bill D

[Rich Engelhardt]

I'd tray a paint roller on an extension handle.

[Maurice Mcmurry]

The adhesive on HVAC foil tape is very good. It does not stick to wood as well as steel or foil. If you have trouble in the further Andrews Hughes's idea of battens could be a help. They could go on after the tape.