The roof of the main debating chamber at Holyrood could be fundamentally flawed, according to a leading civil engineering publication.
Dave Parker said some elements of the roof could be flawed
MSPs have been unable to use the chamber since a beam came loose on 2 March while they were in session.
It later emerged that one of two bolts in the end of the beam was missing.
Now Dave Parker of New Civil Engineer magazine said there could be forces on parts of the roof's structure that are not behaving as expected.
Speaking on BBC Scotland's Holyrood programme, technical editor Mr Parker said the beams should have been compressed in place.
"The problem really is it's not so much a roof, it's more a giant piece of sculpture that actually keeps the rain out as well," he said.
"There's a lot more oak and steel up there than needs to be. It's a very complex structure.
"As a result, some of the struts that should be under compressive forces seem to be undergoing tension.
"For the timber to come out of the connection, it would have to move backwards relative to the metal and the only way it can do that is if tensile force occurs in the member."
For the last two weeks, MSPs have had to meet elsewhere at a cost of more than £100,000.
The wooden beam came loose above MSPs in the chamber
Mr Parker said the design fault would be the responsibility of the parliament's structural engineer, Arup, but said it did not mean the entire roof was unsafe.
He said: "The roof itself is very strong, far stronger than it needs to be, so I don't think there's any risk to the safety of the whole roof.
"It's really a question of one or two elements that make up the roof, especially towards the areas of the roof at the ends."
Arup, which is using a computer model to re-analyse the roof's design, is due to present further findings to MSPs on Friday.
A Scottish Parliament spokesman said it was expected tests on the beam would continue next week.
He added: "Whether the strut was under compression or tension is only one of the various scenarios that Arup is analysing through its computer modelling."