[Fieldfare]

Hi all- I am wanting to cut a rectangular doorway in a barn wall (made of standard concrete blocks). Can anyone give me any tips on how to do this? Angle grinder? if so could you point me in the direction of a decent model?

Thanks 

[bloomer]

how thick are the blocks?

a normal 230mm grinder will only really cut about 6-8cm deep depending on the guards etc so you would have to cut from both sides and it never lines up perfectly so wouldn't be pretty but would do the job.

i have an ebauer 230mm from screwfix mines 110v but they do a 240v as well i spend all summer cutting holes in concrete slabs with mine and they are a lot harder than concrete blocks, mine was about £90 at the time and worth every penny.

make sure you buy a diamond blade they cost £15-£20 for a basic one that will do what you need but it will pay for itself many times over!!!

just remember sensible protection goggles and gloves and a face mask for the dust are a must...

you can buy/hire bigger cutters that will do the job in a single cut but they are a lot more money.

where are you?

[robert waddell]

as bloomer says also you will    also need to fit a concrete lintel or rsj above the door before you cut the opening or the whole wall will colapse   you can also get stihl saws with bigger diameter blades and they have dust suppression kits as well    stay away from angle grinders i had a friend that used one for the same purpose and nearly cut his wrist off and was somebody that was used to working one as well

[Fieldfare]

...Hi- the blocks are 8 inches wide (breeze block size but tighter concrete). Had a look on YouTube and it looks like getting someone in an cutting with a diamond chainsaw or disc cutter may be the way forward (looks quite quick). I may actually take out a section of wall up to the top which is actually better (about 8ft- the rest is wooden battens) so a lintel won't be necessary (I will check that this doesn't compromise the integrity of the rest of the wall in which case I suppose I will need to pop in a tie (I think not but will check).

I'm in South Yorks (Shef. area).

thanks for your help.

[Plantoid]

There are diamond impregnated mortar rakes that are a spindle you put on a power drill and you can usualy get tehem in 4 inch lenghts so working a along a joint from bothe sides 9 bottm one first you can easily drop blocks .
 
Like has been said watch out for the load above the door especially if this has loaded roof trussees
 Its easy enough to  core drill a 3 inch hole every 600 mm and a course above what your taking out , put 600 mm long by 70 mm round woodem needles in aand use a big timber baulk on acro props either side of the wall to support things till you get the lintel in place .. remember to have the lintel at least half a blocks length wider each side of the new door width to spread the load . If the door width gets too wide you may have to build piers inside the barn to take a strongrr lintel .
 You could do worst than looking on line to find out what a square metre of the blocked wall weighs and  and see what you can find out about the truss load ( if applicable ) to help you get the correct lintel .
 You might need building control permissions as well for your own safety and that of anyone else who  passes in or close byb the new door.

[Bangbang]

If the door your fitting is a standard off the shelf, remember to allow tolerance in the opening size you cut
for easy installation. I normally add 20mm. Its a pain in the a** to trim the frame.

[Fieldfare]

...just to complete this thread I have now cut the doorways. A neighbour borrowed a petrol diamond cutting disk machine (4inch). a cut each side was needed (leaving about 1inch in the middle uncut). A bit of judicious drilling and raking out *very hard and stubborn* mortar to get the 1st block out then allowed a 14lb to do the rest very efficiently (2 person job for safety). The 1" "connector" broke easily. The doorway was top to bottomin both cases (so no lintel needed). Don't laugh  but I have popped my new 'medieval style' doors in (made out of pallets, recycled nails/hinges and the cost of a splash of creosote). Picture attached- note that all my doors now come as a standard pallet shaped wide  Just need to tidy the mess at the top (a hot summers day job I think). Anyway it does the job!

Thanks for all your advice!

cheers

[Fieldfare]

...and yes I know it is not straight...I like it that way (I'm proud to say I measured it all by eye) 

[deepinthewoods]

     

[Bangbang]

If it opens and closes without a kick its fine -
looks good from here. 
In Scotland eyeball measurements are used regularly and then labelled as ' giving it
character '.