The Brynmair slant on the Dartington Underfloor entrance

Beekeeping & Apiculture Forum

Help Support Beekeeping & Apiculture Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

jenkinsbrynmair

International Beekeeper of Mystery
***
BeeKeeping Supporter
Joined
Mar 30, 2011
Messages
35,891
Reaction score
15,703
Location
Glanaman,Carmarthenshire,Wales
Hive Type
National
Number of Hives
Too many - but not nearly enough
Years ago I was taken by an open mesh floor designed on the principle of the Dartington hive underfloor entrance, there were plenty of variants kicking around and after some research and modifying I settled on this pattern, now all my hives have these floors. You’ll have to excuse my switching between metric and imperial – my carpentry skills were taught by my father and there are aspects of both measuring systems I like.
Why underfloor entrances? There are many benefits:
Wasps hate them, a combination of having to creep up vertically through the slot and when they pop their heads up above the floor there are ranks of guard bees lined up on each side of the slot – I’ve seen wasps try, and tumble straight out subsequently avoiding the underfloor hives and trying their luck on stronger hives with conventional entrances.
Mice can’t get in through the narrow (between 8 and 10mm) overhead entrance so already you have saved on guards, the fiddle of installing them and the annual debate on when to put them on or remove.
No issues of pollen being knocked off by mouseguards or dead bees blocking the entrance. In midwinter when bees aren’t very active any bees that die and fall near the entrance just fall down or get pushed out onto the landing board below.
No need to reduce the entrance size during winter or when wasps are around – mine stay full width all year.
There is a three inch deep entrance ‘porch’ – bees have no problems landing in a sharp crosswind – even fully laden.

Erichalfbee has asked me to share the plans for my underfloor entrance on here, saves me sending them out each time I get a request, although I still don't mind doing that if asked - this may take more than one post to get all the stuff on.

Construction:
I haven’t specified the lengths of any of the timber as it depends on the type of hive you have. For a National, the side rails would be 18⅛” (460mm) I then set these rails – outer edges 18⅛”apart on my bench and mark all the other components accordingly
First decide on the depth of your floor (either 3 or 4 inches) I prefer 4 inches as it allows more space in the ‘entrance’ I now just use 50x100mm CLS profile timber for the sides which is ideal.

All the timber is off the shelf dimensions which gives you a slight extension to the floor of the entrance lobby, Having a table saw I cut the landing board a little narrower so you haven’t got the extra ½” or so overhang – this just makes it a bit easier to strap up and stack them in a trailer or vehicle when moving hives around.

1) On a flat surface fix your floor batten and rear batten to your two sides:

2) Fix your entrance back to your side rails – I use two 9mm twist drill bits to size the entrance gap, easier than trying to measure/mark fix

3) fix your landing board

4) Then fix two lengths of light timber (½” or ¾” square batten) to the inside of the side rails as runners for the varroa inspection tray.


a piece of correx is fine for an inspection tray – you can tack a wooden batten onto it to close off the whole of the back.

5) All you have left to do now is staple on your varroa mesh.
 

Attachments

  • Floor Diagram 1 .jpeg
    Floor Diagram 1 .jpeg
    82.3 KB · Views: 150
  • Floor Diagram 2The Base.jpeg
    Floor Diagram 2The Base.jpeg
    119.6 KB · Views: 135
  • Floor DIagram 3 Front from Above.jpeg
    Floor DIagram 3 Front from Above.jpeg
    94.3 KB · Views: 135
  • Floor Diagram 5 Side View.jpeg
    Floor Diagram 5 Side View.jpeg
    83.8 KB · Views: 132
  • Floor Diagram 6 Rear Aspect.jpeg
    Floor Diagram 6 Rear Aspect.jpeg
    92.3 KB · Views: 119
Years ago I was taken by an open mesh floor designed on the principle of the Dartington hive underfloor entrance, there were plenty of variants kicking around and after some research and modifying I settled on this pattern, now all my hives have these floors. You’ll have to excuse my switching between metric and imperial – my carpentry skills were taught by my father and there are aspects of both measuring systems I like.
Why underfloor entrances? There are many benefits:
Wasps hate them, a combination of having to creep up vertically through the slot and when they pop their heads up above the floor there are ranks of guard bees lined up on each side of the slot – I’ve seen wasps try, and tumble straight out subsequently avoiding the underfloor hives and trying their luck on stronger hives with conventional entrances.
Mice can’t get in through the narrow (between 8 and 10mm) overhead entrance so already you have saved on guards, the fiddle of installing them and the annual debate on when to put them on or remove.
No issues of pollen being knocked off by mouseguards or dead bees blocking the entrance. In midwinter when bees aren’t very active any bees that die and fall near the entrance just fall down or get pushed out onto the landing board below.
No need to reduce the entrance size during winter or when wasps are around – mine stay full width all year.
There is a three inch deep entrance ‘porch’ – bees have no problems landing in a sharp crosswind – even fully laden.

Erichalfbee has asked me to share the plans for my underfloor entrance on here, saves me sending them out each time I get a request, although I still don't mind doing that if asked - this may take more than one post to get all the stuff on.

Construction:
I haven’t specified the lengths of any of the timber as it depends on the type of hive you have. For a National, the side rails would be 18⅛” (460mm) I then set these rails – outer edges 18⅛”apart on my bench and mark all the other components accordingly
First decide on the depth of your floor (either 3 or 4 inches) I prefer 4 inches as it allows more space in the ‘entrance’ I now just use 50x100mm CLS profile timber for the sides which is ideal.

All the timber is off the shelf dimensions which gives you a slight extension to the floor of the entrance lobby, Having a table saw I cut the landing board a little narrower so you haven’t got the extra ½” or so overhang – this just makes it a bit easier to strap up and stack them in a trailer or vehicle when moving hives around.

1) On a flat surface fix your floor batten and rear batten to your two sides:

2) Fix your entrance back to your side rails – I use two 9mm twist drill bits to size the entrance gap, easier than trying to measure/mark fix

3) fix your landing board

4) Then fix two lengths of light timber (½” or ¾” square batten) to the inside of the side rails as runners for the varroa inspection tray.


a piece of correx is fine for an inspection tray – you can tack a wooden batten onto it to close off the whole of the back.

5) All you have left to do now is staple on your varroa mesh.
Just need a way to work out how to convert the cheap OMF floors I bought 20 of inntbe sales a while ago! Underfloor is definitely the way yo go
 
Beyond keeping wasps out what are the advantages of an under floor? The reason for them seems to have been lost somewhat.
 
Beyond keeping wasps out what are the advantages of an under floor? The reason for them seems to have been lost somewhat.
It’s a good easily constructed floor for about the same money or cheaper as the main suppliers economy floors. What’s the lost reason?
 
The reason for them seems to have been lost somewhat.
You've lost me now - what is this 'lost reason' you go on about?
Easy to build and more robust than the flimsy OMF floors on offer by most equipment seller
Even nowadays, cheaper than off the shelf floors - even 'second quality' ones
Wasps hate them and I find there is no need to reduce the entrances when they're around
Mouse proof - no need for mouse guards and all the fiddle of installing/removing them
the entrance 'lobby makes it easier for bees to land in the wind
No need to reduce entrances in winter - in fact, no need to reduce the entrance, period
they have a built in 'landing board' so easier to transport in numbers as each hive had a standard 460x460mm footprint
simple to shut up for moving - just stuff a piece cut off from an old foam cushion into the entrance 'lobby'
 
Beyond keeping wasps out what are the advantages of an under floor? The reason for them seems to have been lost somewhat.
It increases the hydraulic resistance of the entrance, by increasing the length to apparent diameter ratio. in plain English less drafty, less heat loss. but that only works if you don't have open mesh floor with the tray out or the tray slot not sealed.
 
Last edited:
IMG_5097.jpeg
My take on the excellent JBM OMF. The only change I made (I know - just have to fiddle with stuff) is the entrance doesn’t run the full width. I was was thinking the wasps might try sneaking in at the corners but I’ve been using the floors for a few seasons now and have everything running on them - like JBM I’ve seen wasps try to enter and come tumbling out then content themselves with sniffing around the (tight) joints between boxes. Thank you JBM!
I meant to ask, is anyone else attending the BIBBA conference in Carmarthen on 2nd and 3rd September? Be nice to see people in the flesh, though, hopefully, not too much of it 🫣
Last thing 😧 I screw a rim around the finished floor to provide bee-space. I’ve settled on 20mm which has worked faultlessly so far.
 
Last edited:
View attachment 37423
My take on the excellent JBM OMF. The only change I made (I know - just have to fiddle with stuff) is the entrance doesn’t run the full width. I was was thinking the wasps might try sneaking in at the corners but I’ve been using the floors for a few seasons now and have everything running on them - like JBM I’ve seen wasps try to enter and come tumbling out then content themselves with sniffing around the (tight) joints between boxes. Thank you JBM!
I meant to ask, is anyone else attending the BIBBA conference in Carmarthen on 2nd and 3rd September? Be nice to see people in the flesh, though, hopefully, not too much of it 🫣
Last thing 😧 I screw a rim around the finished floor to provide bee-space. I’ve settled on 20mm which has worked faultlessly so far.
If you put a 8mm hole in the rim you can vape through it. I seal mine when not in use with an 8mm bolt.
 

Latest posts

Back
Top