These instructions apply to both Anglo-Saxon and Viking Grubhouse kits and to the Cottage kit.
The term is from the German word Grubenhaus and is also known in English as a "Pit House". The house itself would have been created as a rectangular hole in the ground - with the house build almost as a roof over the hole. So while the entrance would be rather low - there would be plenty of room to stand up inside. Sometimes the pit inside would be lines with rocks - sometimes with wood or even sod or peat. Grubhuts have been used since prehistory and even into the present day in some cultures. They had roofs of wood, thatch, sod, woven branches with daub...whatever was available locally.
As always - if you intend to paint the model, you should paint all of the parts BEFORE assembly. It's much easier that way. I recommend painting the solid "inner" wall pieces in a creamy white - then dry brush with browns and a little dull green to make it look dirty. All of the other wooden beams should be in a dark brown, possibly very lightly dry brushed with a mid grey. The horned pieces that go on either end of the roof could be painted in a bright color to aid identification of which building is which...or not, as you feel.
As you remove the parts - keep a couple of the triangular "waste" parts lying around:
First locate the inner and outer walls. The two different GrubHouse kits have slightly different designs. The Cottage kit has much taller walls - but is otherwise the same.
Glue the outer walls onto the inner walls. Pay attention to the tabs and slots on the walls - the orientation matters when it comes to assembling the walls together. If you purchased multiple kits - you can actually assemble it with all of the walls flipped over to make a mirror image of the standard building to get some additional variability.
Glue the four walls together.
Use those left over triangular waste parts to help you get everything square and upright - but don't glue them to the walls!
As the glue sets on the walls - let's assemble the inner frame:
I find it easiest to first glue the three beams to the center A-frame:
...then to add the A frames at the two ends:
Before the glue completely sets - place the frame into the walls that you already assembled (DON'T GLUE THEM) so you can be sure that they'll fit when they glue dries...
...glue the support bracket on the wall with the small square hole in it (the Cottage kit doesn't have this) - and assemble the roof board and two decorative end pieces:
If you have the thatched roof version, we recommend that you carefully trim back the foam backing for a few millimeters (maybe a tenth of an inch) so that the thatch can drape over the ends a bit. If you have the sod roof version, then remove any loose bits of lichen to clean it up as needed. In both cases, the roof material should fit to the ends of the entire building at the ends, and hang over the sides by maybe 5mm.
Glue the material to the inner frame of the building ONLY. DO NOT glue it to the actual walls. The idea here is to be able to remove the roof (along with the inner frame) if you need to move figurines around inside the building.
Finally - you can either omit the roof board - or glue it onto the top of the roof - real GrubHuts were sometimes built one way - and sometimes the other.