Best fittings?

A 2m roller blind takes a fair amount of pull to roll up/down so, best to drill through PB and void and drill and fix into lintel

Is lintel steel or concrete would you know ?

And no option to side fix brackets then ?

 

Had a similar issue trying to get good fixings for two long vertical blinds across a 3M wide opening for my French doors into the rear garden. Found it near impossible to drill into the lintel, being upside down and the holes running off centre. There was no option for any fitting into the sides of the window opening.
A double thickness of plaster board and dab on the underside of the lintel where the blinds needed to be hung. Decided to cut out oblongs about 25mm x 50mm in the plasterboard at each fixing point, cleaned right back to the underside of the lintel. Cut some slighty smaller plywood strips which I bonded together to be just short of the depth of the plasterwork. Once I'd got enough pieces assembled i then bonded the prepared plywood pieces together. In turn bonded the thick plywood to the underside of the clean steel lintel. Filled over and around the plywood with Polyfiller and when dry sanded back smooth to match the existing plaster. Hardly noticable when down, just needed a coat of paint.
I had my doubts about this providing a decent fixing as I could only use relatively short screws to hold the six brackets. Wasn't disappointed!! Everything went up without any problems and has stayed up without moving at all in 3years. Doing this also allowed me to get the fixings adjusted exactly where needed as could screw directly into the bonded ply.
I used a sealer adhesive which I found to be excellent in the past called CT1, it cures like a hard type rubber but stays flexible, it's suitable for almost any surface. There are other equivalents to CT1 on the market.
Was more faff than I wanted but the strength of the fixing I got was really good as the area bond to the lintel is relatively large and the screws held tight in the ply.
Might work for your roller blind but perhaps use larger pieces of ply/timber. Went for ply as it's better having the crossed grain and stops splitting.

 

I've drilled into steel lintels to pre-fit battens
to support the inevitable blinds.
Wouldn't attempt fixing roller brackets direct
to your lintel / dot'n'dab set up as Mark's Dad
said holes run off centre , and the brackets
wouldn't accommodate the thicker diameter
self -tappers.

 

Many roller blind brackets allow for some adjustment once fixed as have either slots for screws which allow fine adjustment or ‘+’ type slots which again allow adjustment

A size 4 -5 screw should be fine, wether fixing into steel lintel or screw and plug into concrete, again these will slip through the brackets

 

I can only speak from my experiences, self tappers
going into steel lintel need torx or hex head.
Not the same as self tapping some ply into
the inside of a Transit. They're not 4 or 6
gauge size.

 

Drill a couple of test holes to hit the lintel to give an indication of what material it is - concrete / steel / sounds and feels different via drill bit and the dust will let you know also

100 year old house - lintel could even be timber / in that case, and only a possibility at this stage, then nothing more than a wood screw required

 

Our local company NU Blinds use self drilling screws direct into steel lintle in your recess or 5.5 mm sds bit into concrete then plug and screw with 6mm plug